CN110785806A

CN110785806A - Sound insulation system

Info

Publication number: CN110785806A
Application number: CN201880041561.2A
Authority: CN
Inventors: 大津晓彦; 白田真也; 山添昇吾
Original assignee: Fujifilm Corp
Current assignee: Fujifilm Corp
Priority date: 2017-06-21
Filing date: 2018-06-19
Publication date: 2020-02-11
Anticipated expiration: 2038-06-19
Also published as: JPWO2018235797A1; WO2018235797A1; CN110785806B; EP3644308A4; EP3644308A1; US11580948B2; US20200126532A1; JP6960454B2; EP3644308B1

Abstract

The sound insulation system of the present invention comprises: a tube structure having more than 1 open end; and a sound insulation structure having an opening or a radiation surface, wherein when a phase difference of reradiated sound with respect to incident sound to the sound insulation structure is represented by θ 1, a distance between the opening or the radiation surface and a position of the pipe structure where sound pressure is a maximum value is represented by L, and a wavelength of the incident sound is represented by λ, and the phase difference θ 2 is defined as 2 π × 2L/λ, with respect to a maximum value of 1 or more sound pressures formed in the pipe structure, the following formula (1) is satisfied. The sound insulation system can obtain a large transmission loss in a wide frequency band with a small size. The | [ theta ] 1-theta 2| < pi/2 … … (1).

Description

Sound insulation system

Technical Field

The present invention relates to a sound insulation system having a pipe structure and a sound insulation structure. More particularly, the present invention relates to a sound insulation system for reducing sound over a wide frequency band while maintaining air permeability in an air permeable pipe structure such as a duct, a muffler, or a ventilation sleeve, thereby performing sound insulation.

Background

Conventionally, a structure which assumes that air permeability of a duct, a muffler, a ventilation sleeve, and the like is ensured passes air, wind, or heat and sound, and therefore, it is sometimes required to take a measure against noise. Therefore, in particular, in applications where the pipe or the muffler is mounted on a noisy machine, it is necessary to design the structure of the pipe or the muffler to perform sound insulation (see patent documents 1 and 2).

The technique described in patent document 1 is an air conditioning silencer system in which 2 or more resonance silencers (for example, 2 or more tubes having substantially the same length) for silencing noise in substantially the same set frequency region are attached to the middle of a pipe of an air conditioning duct, and the distance d between the attachment positions (for example, the openings of the tubes) of the adjacent resonance silencers satisfies the condition of λ/12+ n λ/2 ≦ d ≦ 5 λ/12+ n λ/2.

Generally, a cylindrical gas column resonator exhibits the highest effect when its opening is provided near the antinode of sound pressure, and the effect is low when the opening is provided near the node of sound pressure. Therefore, if the number of resonance-type silencers such as a gas column resonance tube is 1, if the position is arbitrarily determined, the transmission loss of sound is reduced when the opening portion is located in the vicinity of the node. In order to avoid this phenomenon, the technique disclosed in patent document 1 is such that the opening interval d between the adjacent 2 cylindrical gas column resonance tubes set to be substantially the same length satisfies the above condition. This makes use of a mechanism in which at least one of the 2 cylindrical gas column resonance tubes is located at a position distant from the node, and the transmission loss is improved.

In the technique described in patent document 2, a tubular silencing body having a length half of the length of a sleeve is provided in the sleeve of the natural ventilation port, and a porous material is disposed inside the tubular silencing body.

In the technique disclosed in patent document 2, the natural frequency of the sleeve and the natural frequency of the sound deadening tubular body are made to coincide with each other 1 st order, and the sound pressure characteristics of the sleeve and the sound deadening tubular body are shifted, whereby the air column resonance of the sleeve is reduced, and the sound deadening effect is obtained by the air column resonance effect of the sound deadening tubular body. Further, in the technique of patent document 2, the sound absorbing bandwidth is widened by inserting the porous material into the air column resonance pipe, and the frequency band sound in which the sound insulating performance is lost is effectively absorbed by the air column resonance, so that the sound absorbing effect can be widened (enlarged).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2005-307895

Patent document 2: japanese patent laid-open publication No. 2016-095070

Disclosure of Invention

Technical problem to be solved by the invention

However, in the technique of

patent document

1, 2 cylindrical air column resonance tubes having the same length are provided adjacent to each other in the air-conditioning duct, and at least one of the 2 tubes is made to avoid a node of the sound pressure, thereby improving the noise reduction effect. However, the technique of patent document 1 uses only the principle of air column resonance in order to obtain transmission loss of sound, and has a problem that no consideration is given to the mode of the air-conditioning duct itself. Further, for example, in [ fig. 2] of patent document 1, although the site dependency of the transmission loss is shown, this shows a graph relating to the transmission loss of sound at the resonance frequency of the tube, and there is a problem that the transmission loss of sound at the off-resonance frequency is not described, and no consideration is given to the structure for increasing the transmission loss at the off-resonance frequency.

That is, the technique of patent document 1 aims to dispose 2 tubular gas column resonance tubes having substantially the same resonance frequency in a pipe, so that even if one of the tubes does not function, the other tube functions. Therefore, even if one of the 2 pipes is arranged at the optimum position, the other pipe does not operate effectively, which may cause waste, and the mode of the pipe itself may not be considered.

Further, the technique of patent document 2 is based on a principle called air column resonance, but the size of the sound-deadening tubular body depends on the size of the casing, and the air column resonance of the casing is weakened to improve sound-deadening performance, and the sound-deadening frequency band is limited, so that it is necessary to use a porous material for the purpose of widening the frequency, and the basic principle is based on a principle based on air column resonance and widening of the frequency of the porous material. That is, the technique of patent document 2 utilizes air column resonance, and further obtains an effect of enlarging a resonance peak of transmission loss by a necessary porous body.

However, in order to obtain a high transmission loss at a desired frequency, it is considered to be one of the measures to provide a resonance type sound insulating structure (for example, a helmholtz resonator, an air column resonance tube, a membrane vibration type structure, or the like) and insulate the resonance frequency, as in the techniques of

patent documents

1 and 2.

However, it is generally difficult to provide a large number of sound insulating members in a duct or a muffler due to space limitations, and therefore, there is a case where a sound insulating structure needs to be downsized. In general, when sound at a low frequency is absorbed by resonance phenomenon, the size of the sound insulation structure corresponding to the wavelength is increased because the wavelength is long. These are problems that cause a disadvantage of reducing the air permeability of the pipe or the muffler.

Further, the resonance type sound insulation structure is generally narrow in sound insulation band, and it is difficult to simultaneously eliminate noise at a plurality of frequencies or a wide band. On the other hand, the sound insulation performance of a general porous sound absorbing material such as polyurethane or glass wool is particularly low on the low frequency side. At frequencies of 1000Hz or less, there is a problem that the porous sound absorbing material is hardly effective even when it is disposed in a duct or the like.

That is, these conventional techniques have a problem that sound on the low frequency side cannot be isolated with a size smaller than the wavelength size, and a problem that sound on the wide frequency band cannot be isolated with a small structure particularly on the low frequency side.

The present invention has been made to solve the above-described problems and problems of the conventional art, and an object of the present invention is to provide a sound insulation system that can obtain a large transmission loss in a wide frequency band with a small size.

In addition to the above object, the present invention has an object to provide a sound insulation system including a pipe structure and a sound insulation structure having an opening, wherein the sound insulation structure is disposed at an optimum position, thereby realizing a reduction in size of the sound insulation structure in the sound insulation system, having a function of ensuring a ventilation sound insulation with high ventilation, and further, obtaining high transmission loss in a wider frequency band than in the conventional art.

Here, in the present invention, "sound insulation" includes both the meanings of "sound insulation" and "sound absorption" as acoustic characteristics, but particularly refers to "sound insulation". Further, "sound insulation" refers to a case of "shielding sound". That is, "sound insulation" means "sound is not transmitted. Therefore, the case of "reflecting" sound (reflection of sound) and the case of "absorbing" sound (absorption of sound) are included and referred to as "sound insulation". (refer to the pages http:// www.onzai.or.jp/query/soundproduof. html and http:// www.onzai.or.jp/pdf/new/gijutsu201312_3.pdf) of the university of Otsu (third edition) of the three provinces and the society of acoustical materials of Japan.

Hereinafter, "reflection" and "absorption" are not substantially distinguished, and "sound insulation" and "shielding" are referred to as "sound insulation" and "absorption" when both are distinguished.

Mechanism for solving technical problem

In order to achieve the above object, a sound insulation system according to claim 1 of the present invention has a tube structure having 1 or more open ends, and a sound insulation structure, wherein the sound insulation structure has an opening or a radiation surface on which sound is incident or radiated, the opening or the radiation surface of the sound insulation structure is disposed on an inner side of the tube structure, a phase difference of a reradiated sound reradiated from the sound insulation structure with respect to an incident sound incident on the sound insulation structure is defined as θ 1, a preferable range of the phase difference θ 1 is defined as 0 to 2 π, a distance between the opening or the radiation surface of the sound insulation structure and a position of the tube structure where sound pressure becomes maximum with respect to 1 or more maximum values of sound pressure of sound which forms sound pressure distribution in the tube structure is defined as L, a wavelength of the incident sound incident on the sound insulation structure is defined as λ, and the phase difference θ 2 is defined as 2 pi × 2L/λ, the following formula (1) is satisfied.

|θ1-θ2|≤π/2……(1)

Here, the sound that forms the sound pressure distribution in the pipe structure is preferably sound of the same frequency or wavelength as the incident sound that enters the sound insulating structure.

Further, the sound insulation structure is preferably a resonator for sound waves.

Also, the maximum value is preferably an antinode of a standing wave of sound formed by the pipe structure.

Preferably, the tube structure has resonance, and satisfies the above formula (1) at a frequency at which the resonance occurs.

Preferably, the sound insulating structure is a tubular body having an opening.

Preferably, the formula (1) is satisfied at a frequency different from the resonance frequency of the tubular body.

Further, it is preferable that the transmission loss is maximized at a frequency satisfying the above formula (1).

Preferably, the tubular body has a resonance frequency fr [ Hz ]]Among frequencies at which the transmission loss becomes minimum and smaller than the resonance frequency fr in the transmission loss spectrum of the pipe structure, the frequency fma [ Hz ] at the maximum is]In the above description, La1 represents a distance between the opening of the tubular body and a position of the tubular structure closest to the opening on the same side as the sound propagation direction in the frequency fma and having a maximum sound pressure value, and λ represents a wavelength in the frequency fma _fmaThen, the following formula (2) is satisfied.

0≤La1≤λ _fma/4……(2)

In order to achieve the above object, a sound insulation system according to claim 2 of the present invention has a pipe structure having 1 or more open ends, and a sound insulation structure, wherein the sound insulation structure is a tubular body having an opening, and the tubular body has a resonance frequency fr [ Hz ] Hz]Among frequencies at which the transmission loss becomes minimum and smaller than the resonance frequency fr in the transmission loss spectrum of the pipe structure, the frequency fma [ Hz ] at the maximum is]In the above description, La1 represents a distance between the opening of the tubular body and a position of the tubular structure closest to the opening on the same side as the sound propagation direction in the frequency fma and having a maximum sound pressure value, and λ represents a wavelength in the frequency fma _fmaThen, the following formula (2) is satisfied.

0≤La1≤λ _fma/4……(2)

Further, it is preferable that the following formula (3) is satisfied when the length of the back surface of the tubular body is defined as d.

d＜λ _fma/4……(3)

Preferably, the opening of the tubular body is provided at a distance λ from the open end of the tube structure _fmaInside the position.

Preferably, the tubular body has a resonance frequency fr [ Hz ]]Among frequencies at which the transmission loss becomes minimum and greater than the resonance frequency fr in the transmission loss spectrum of the tube structure, the minimum frequency fmb [ Hz ]]La2 is the distance between the opening of the tubular body and the position of the tubular structure closest to the opening on the same side as the sound propagation direction in the frequency fmb and having the maximum sound pressure, and λ is the wavelength in the frequency fmb _fmbThen, the following formula (4) is satisfied.

λ _fmb/4≤La2≤λ _fmb/2……(4)

In order to achieve the above object, a sound insulation system according to claim 3 of the present invention has a pipe structure having 1 or more open ends, and a sound insulation structure, wherein the sound insulation structure is a tubular body having an opening, and the tubular body has a resonance frequency fr [ Hz ] Hz]In a frequency where the transmission loss becomes minimum and is larger than the resonance frequency fr in the transmission loss spectrum of the tube structure,at a minimum frequency fmb [ Hz]La2 is the distance between the opening of the tubular body and the position of the tubular structure closest to the opening on the same side as the sound propagation direction in the frequency fmb and having the maximum sound pressure, and λ is the wavelength in the frequency fmb _fmbThen, the following formula (4) is satisfied.

λ _fmb/4≤La2≤λ _fmb/2……(4)

Preferably, the opening of the tubular body is provided at a distance λ from the open end of the tube structure _fmbInside the position.

Further, the opening of the tubular body is preferably located at a position different from a node of a standing wave of sound formed by the pipe structure.

Further, the opening or the radiation surface of the sound insulating structure is preferably provided at a position within a wavelength λ from the opening end of the tube structure.

Further, it is preferable that the sound insulating structure is built in the pipe structure.

Preferably, the number of the sound insulation structures disposed inside the pipe structure is 2 or more.

Preferably, a sound absorbing material is further provided inside the pipe structure.

Further, the sound absorbing material is preferably provided on at least a part of the sound insulation structure.

Further, the pipe structure and the sound insulating structure are preferably integrally molded.

Further, it is preferable that the sound insulating structure is attachable to and detachable from the pipe structure.

Further, the sound insulation structure is preferably a helmholtz resonator.

Further, it is preferable that fr is 1000Hz or less when the sound-insulating structure has a resonance frequency fr [ Hz ].

Also, the tube structure is preferably curved.

Effects of the invention

According to the sound insulation system of the present invention, a large transmission loss can be obtained in a wide frequency band with a small size.

According to the present invention, it is possible to provide a sound insulation system including a pipe structure and a sound insulation structure having an opening, wherein the sound insulation structure is disposed at an optimum position, thereby achieving a reduction in size of the sound insulation structure in the sound insulation system, and having a function of sound insulation with ventilation that ensures high ventilation, and further, for obtaining high transmission loss in a wider frequency band than in the conventional art.

Drawings

Fig. 1 is a schematic cross-sectional view showing an example of a sound insulation system according to an embodiment of the present invention.

Fig. 2 is a schematic perspective view of a tube structure used in the sound insulation system shown in fig. 1.

Fig. 3 is a schematic perspective view of a sound insulating structure used in the sound insulating system shown in fig. 1.

Fig. 4A is a schematic cross-sectional view illustrating a standing wave of one frequency formed in a tube structure used in the sound insulation system shown in fig. 1.

Fig. 4B is a schematic cross-sectional view illustrating a standing wave of another frequency formed in the tube structure used in the sound insulation system shown in fig. 1.

Fig. 4C is a graph showing a relationship between a distance from the open end of the tube structure shown in fig. 4A and a sound pressure distribution of a standing wave of one frequency.

Fig. 4D is a graph showing a relationship between a distance from the open end of the tube structure shown in fig. 4B and a sound pressure distribution of a standing wave of another frequency.

Fig. 5 is a graph showing a relationship between transmission loss and frequency of the tube structure shown in fig. 4A and 4B.

Fig. 6 is a schematic cross-sectional view illustrating a sound insulation principle of an embodiment of the present invention in the sound insulation system shown in fig. 1.

Fig. 7 is a schematic cross-sectional view illustrating a sound insulation principle of another embodiment of the present invention in the sound insulation system shown in fig. 1.

Fig. 8 is a schematic cross-sectional view illustrating a sound insulation principle of another embodiment of the present invention in the sound insulation system shown in fig. 1.

Fig. 9 is a graph showing the relationship between transmission loss and frequency of the sound insulation system of the present invention.

Fig. 10 is a graph showing the relationship between transmission loss and frequency of a sound insulation system according to another embodiment of the present invention.

Fig. 11 is a schematic cross-sectional view of another example of the sound insulation system of the present invention.

Fig. 12 is a graph showing a relationship between transmission loss and frequency in an example of the sound insulation system of the present invention.

Fig. 13 is a graph showing the relationship between transmission loss and frequency of the sound insulation system shown in fig. 11.

Fig. 14 is a schematic cross-sectional view of an example of a sound insulating system according to another embodiment of the present invention.

Fig. 15 is a graph showing the relationship between transmission loss and frequency of the soundproof system shown in fig. 14.

Fig. 16 is a schematic cross-sectional view of an example of a sound insulation system according to another embodiment of the present invention.

Fig. 17 is a graph showing the relationship between transmission loss and frequency of the sound insulation system shown in fig. 16.

Fig. 18 is a schematic cross-sectional view of an example of a sound insulation system according to another embodiment of the present invention.

Fig. 19 is a graph showing the relationship between transmission loss and frequency of the sound insulation system shown in fig. 18.

Fig. 20 is a schematic cross-sectional view of an example of a sound insulating system according to another embodiment of the present invention.

Fig. 21 is a schematic perspective view of an example of the sound insulation system shown in fig. 20.

Fig. 22 is a schematic cross-sectional view illustrating a sound insulation principle of an embodiment of the present invention in the sound insulation system shown in fig. 21.

Fig. 23 is a graph showing a relationship between the transmission loss and the absolute value of the difference in phase difference in the sound insulation system shown in fig. 21.

Fig. 24 is a graph showing the relationship between transmission loss and frequency of the sound insulation system shown in fig. 21.

Fig. 25 is a schematic cross-sectional view of an example of a sound insulating system according to another embodiment of the present invention.

Fig. 26 is a schematic cross-sectional view of an example of a sound insulating system according to another embodiment of the present invention.

Fig. 27 is a graph showing the relationship between the transmission loss and the frequency of the sound insulation systems of examples 1 to 4 of the present invention and comparative examples 1 to 3.

FIG. 28 is a graph showing the relationship between transmission loss and frequency of the sound-insulating systems of examples 5 to 7 of the present invention and comparative examples 4 to 5.

Fig. 29 is a graph showing the relationship between the transmission loss and the absolute value of the difference in phase difference in the sound-insulating systems of examples 1 to 4 and comparative examples 1 to 3 of the present invention.

Fig. 30 is a graph showing the relationship between the transmission loss and the frequency of the sound insulation systems of examples 8 to 9 of the present invention and comparative examples 6 to 7.

FIG. 31 is a graph showing the relationship between transmission loss and frequency of the sound-insulating systems of examples 10 to 11 of the present invention and comparative examples 8 to 9.

Fig. 32 is a schematic cross-sectional view of an example of a sound insulating system according to another embodiment of the present invention.

Fig. 33 is a graph showing the relationship between transmission loss and frequency of the sound insulation system shown in fig. 32.

Fig. 34 is a schematic cross-sectional view of an example of a sound insulating system according to another embodiment of the present invention.

Fig. 35 is a schematic enlarged cross-sectional view of an example of a sound absorbing body that can be replaced with respect to the pipe structure of the sound insulation system shown in fig. 34.

Fig. 36 is a schematic cross-sectional view of an example of a sound insulating system according to another embodiment of the present invention.

Fig. 37 is a graph showing the relationship between transmission loss and frequency of the sound insulation system shown in fig. 35.

Fig. 38 is a schematic cross-sectional view of an example of a sound insulating system according to another embodiment of the present invention.

Fig. 39 is a schematic cross-sectional view of an example of an exchangeable sound insulating structure of the sound insulating system shown in fig. 38.

Fig. 40 is a schematic cross-sectional view of an example of a sound insulation system according to another embodiment of the present invention.

Fig. 41 is a schematic cross-sectional view of an example of a sound insulating system according to another embodiment of the present invention.

Fig. 42 is a schematic cross-sectional view of an example of a sound insulating system according to another embodiment of the present invention.

Fig. 43 is a schematic cross-sectional view of an example of a sound insulating system according to another embodiment of the present invention.

Fig. 44 is a schematic cross-sectional view of an example of a sound insulation system according to another embodiment of the present invention.

Fig. 45 is a schematic cross-sectional view of an example of a sound insulating system according to another embodiment of the present invention.

Detailed Description

Hereinafter, the sound insulation system according to the present invention will be described in detail with reference to preferred embodiments shown in the drawings.

Hereinafter, a case will be described as a typical example in which a pipe structure having a right-angled connecting bent pipe shape (hereinafter, also referred to as an L-shaped pipe shape) is used as the pipe structure, and a tubular body having a slit-shaped opening portion disposed inside the pipe structure is used as the sound insulating structure.

Fig. 1 is a cross-sectional view schematically showing an example of a sound insulation system according to an embodiment of the present invention. Fig. 2 is a schematic perspective view of a tube structure used in the sound insulation system shown in fig. 1. Fig. 3 is a schematic perspective view of a sound insulating structure used in the sound insulating system shown in fig. 1.

A sound insulation system 10 according to an embodiment of the present invention shown in fig. 1, 2, and 3 includes an L-shaped tubular structure 12 such as an L-shaped tubular duct, and a tubular body 14 disposed inside the tubular structure 12 and serving as a sound insulation structure.

The pipe structure 12 includes a straight pipe portion 16 having a rectangular cross section and a bent portion 18 having a rectangular cross section and bent at a right angle from the straight pipe portion 16. One end of the straight tube portion 16 constitutes an open end 20, and the other end is connected to the bent portion 18. One end of the bent portion 18 also constitutes an open end 22, and the other end is connected to the other end of the straight tube portion 16. The tube structure 12 resonates at a specific frequency and functions as an air column resonator. In the present invention, the term "bent" does not mean that the bent angle is not limited to pi/2 (90 °), but means that the bent angle is 5 ° or more, as shown in fig. 1.

The tubular body 14 is disposed inside the straight tube portion 16 of the tube structure 12 and on the bottom surface 16a of the straight tube portion 16. Details of the arrangement position of the tubular body 14 in the pipe structure 12 will be described later. The tubular body 14 has a rectangular parallelepiped shape. The tubular body 14 is a sound insulating structure that functions as an air column resonator.

In this manner, the sound insulating structure is preferably a tubular body 14 having an opening 24 for a resonator of sound waves.

The tubular body 14 has a slit-like opening 24 formed along 1 end surface. The opening 24 of the tubular body 14 is an opening through which sound is incident or radiated. Here, the opening 24 is disposed inside the pipe structure 12 (for example, inside the straight pipe portion 16). Instead of the opening 24, the tubular body 14 may have a radiation surface on which sound is incident or radiated.

The sound insulation system 10 of the present invention uses a sound insulation structure composed of a tubular structure 12 and a tubular body 14, each having an L-shaped tubular shape, and is configured to optimize (1) the resonance mode inherent to the tubular structure 12, (2) the position of the opening 24 of the tubular body 14 as the sound insulation structure, and (3) the length of the back surface (back surface distance) of the tubular body 14 as the sound insulation structure.

That is, in the present invention, by disposing the tubular body 14 as the sound insulating structure at an optimum position in the pipe structure 12, (i) a peak value of transmission loss due to air column resonance and (ii) a peak value of transmission loss due to a pipe coupling mode (non-resonance) which is a basic principle of the present invention described later can be obtained. In the conventional technique, the peak of the transmission loss is only the peak of the air column resonance, but in the present invention, the peak due to the off-resonance can be obtained by optimizing the parameters (1) to (3) described above.

In the present invention, the off-resonance peak can be expressed as described above, and the off-resonance peak are combined to express not only the transmission loss due to resonance but also the off-resonance transmission loss, whereby a wide band of transmission loss can be obtained without using a porous material or the like as in patent document 2.

The mechanism of the basic principle of the present invention, i.e., the pipe coupling mode, will be described in detail with reference to fig. 4A to 4D and fig. 5.

Fig. 4A and 4B are schematic cross-sectional views respectively showing standing waves of different frequencies formed in the pipe structure used in the sound insulation system shown in fig. 1. Fig. 4C and 4D are graphs showing the relationship between the distance from the open end of the tube structure shown in fig. 4A and 4B and the sound pressure distribution of standing waves of different frequencies, respectively. Fig. 5 is a graph showing a relationship between transmission loss and frequency of the tube structure shown in fig. 4A and 4B.

In the present invention, as shown in fig. 4A and 4B, sound propagating from a sound source (speaker) 26 attached to the open end 22 of the curved portion 18 of the tube structure 12 propagates in the direction indicated by the arrow a, and is radiated from the open end 20 of the straight tube portion 16 of the tube structure 12. The sound radiated from the open end 20 is measured by a measuring device such as a microphone 28 disposed on the open end 20 side.

In the pipe structure 12 such as a duct having 1 or more open ends 20 shown in fig. 4A and 4B, there are both easy-to-pass sound frequencies and difficult-to-pass sound frequencies that are uniquely determined according to the structural dimensions (e.g., size, dimensions, etc.) of the pipe structure 12. That is, the pipe structure 12 itself operates as a sound selection filter, and the filtering performance thereof is determined by the pipe structure 12. This is because, as shown in fig. 4A and 4B, sound of a certain specific frequency (600Hz in fig. 4A and 1000Hz in fig. 4B) or wavelength corresponding to the size and shape of the pipe structure 12 forms a uniform and stable standing wave (i.e., a pattern) inside the pipe structure 12, and sound forming such a pattern is particularly likely to be emitted from the pipe structure 12. In the example shown in fig. 4A and 4B, the straight tube portion 16 of the tube structure 12 has a dimension of 88mm × 163mm (cross section) × 394mm (length), and the bent portion 18 has a dimension of 64mm × 163mm (cross section) × 27mm (length). The example shown in fig. 4A is a 600Hz sound mode (standing wave) in this case, and is a mode having antinodes a (antinodes) on both sides and a node n (node) between them. The example shown in fig. 4B is a 1000Hz sound mode (standing wave) in this case, and has antinodes a at both sides and the center thereof and a node N between adjacent antinodes a. In the present invention, when the absolute value of the sound pressure is measured along the waveguide of the pipe structure 12 by the measuring microphone 28, the position (portion) where the absolute value of the sound pressure is the largest is defined as the antinode a of the sound pressure, and the position (portion) where the absolute value of the sound pressure is the smallest is defined as the node N of the sound pressure.

Fig. 4C and 4D are graphs showing the structure of measuring the sound pressure (absolute value) while shifting the tip of the measuring microphone 28 by 1cm each time from the vicinity of the waveguide cross-sectional center of the open end 20 of the pipe structure 12 toward the back side of the pipe structure 12, and the results are measured at 600Hz and 1000Hz, respectively. In the graphs shown in fig. 4C and 4D, it is understood that the position showing the maximum value of the sound pressure is the position of the antinode a of the sound pressure shown in fig. 4A and 4B, and the position showing the minimum value of the sound pressure is the position of the node N of the sound pressure shown in fig. 4A and 4B. Here, the position closest to the open end 20 of the pipe structure 12, which is the maximum value of sound pressure (antinode a), is 10cm (600Hz) or 5cm (1000 Hz).

However, in the tube structure 12, a mode is formed in which emission from the tube structure 12 is easy among a plurality of frequencies, and as shown in fig. 5, frequencies fm1, fm2(600Hz), and fm3(1000Hz) … … at which transmission loss becomes the minimum appear. That is, the resonance of the tube structure 12 can be defined as occurring in a frequency having a minimum value in the frequency dependence of the transmission loss.

In other words, the frequency at which the transmission loss becomes minimum can also be referred to as the frequency at which the mode is formed. The formation mode is a mode in which, when the pipe structure 12 is an L-shaped pipe, for example, a λ/4 air column resonance appears at a frequency satisfying L0 ═ (2n +1) λ/4, and this resonance phenomenon appears when the distance from the opening of the pipe to the L-shaped portion is L0.

In the drawings and simulation results shown below, the dimensions of the tube structure 12 are as described above. The position of the sound source (speaker) 26 is the position of the open end 22 of the bent portion 18 of the tube structure 12. The microphone 28 is disposed at a distance of 500mm from the open end 20 and 500mm above the bottom surface 16a of the straight tube portion 16.

According to the study of the present inventors, it has been found that, in the pipe structure 12, as shown in fig. 6, by using a sound insulating structure such as the tubular body 14 having the opening 24, it is possible to escape a stable mode to the sound insulating structure 14 side, and it is possible to make sound emission difficult (i.e., increase transmission loss). It is determined that there is an optimum position for the sound-insulating structure 14 side to escape the stable mode with respect to the placement portion of the sound-insulating structure 14 having the opening 24.

In other words, it is considered that the reason is that a stable mode unique to the pipe structure 12 formed only by the pipe structure 12 changes when a sound insulating structure such as the tubular body 14 is provided, and a pipe coupling mode, which is a stable mode, is formed on a path connecting the pipe structure 12 and the sound insulating structure (the tubular body 14), and therefore, sound is confined in this portion.

Further, the reradiated sound of the sound escaping to the sound insulating structure side of the tubular body 14 or the like interferes with the sound returning in the pipe structure 12 to be enhanced, whereby an effect that the sound is more difficult to be emitted to the outlet side of the pipe structure 12 also appears.

(embodiment 1)

However, the present inventors have found that the following requirements are required to simultaneously exhibit the increase in the transmission loss in the above (i) and (ii).

In embodiment 1 of the present invention, for a sound incident on a sound insulating structure such as a tubular body 14, the following equation (1) is satisfied where θ 1[ rad ] ] is defined as a phase difference of a sound re-radiated from the sound insulating structure 14 with respect to the incident sound, L is a distance between a position of an opening 24 or a radiation surface of the sound insulating structure such as the tubular body 14 and a position of the tubular structure 12 where the sound pressure becomes a maximum value, and λ is a wavelength of the sound, and θ 2[ rad ] × 2L/λ [ rad ] ] is defined as a phase difference with respect to at least 1 or more maximum values of the sound pressure formed in the tubular structure 12.

|θ1-θ2|≤π/2[rad.]……(1)

Here, the phase difference θ 1[ rad ] between the sound re-radiated from the sound insulation structure 14 and the incident sound is preferably in the range of 0 to 2 pi. Namely, 0. ltoreq. theta.1. ltoreq.2 π.

In the present invention, the preferable range of the phase difference θ 1 is 0 to 2 pi, and it is assumed that even when the phase difference θ 1 is out of the range of 0 to 2 pi, for example, even when θ 1 is θ s +2n pi (where 0 θ s 2 pi and n is an integer), θ 1 is regarded as θ s, that is, in the present invention, it is entirely synonymous with θ 1 θ s.

In the following, the unit of phase difference [ rad ] is omitted.

Here, the sound pressure of the sound generated in the pipe structure 12 refers to the sound pressure of the sound generating the sound pressure distribution in the pipe structure 12, and is preferably the sound pressure of the sound generating the standing wave in the pipe structure 12. In the present invention, the sound that forms the sound pressure distribution in the pipe structure 12 is preferably a sound having the same frequency or wavelength as the incident sound that enters the tubular body 14 that is the sound insulating structure.

The frequency or wavelength of the sound to be targeted in the present invention is the frequency or wavelength of the sound that forms the sound pressure distribution in the pipe structure 12, and is the same frequency or wavelength as the incident sound that enters the tubular body 14 that is the sound-insulating structure. The frequency or wavelength of the sound is preferably, for example, a wavelength of sound of a certain specific frequency or wavelength corresponding to the size and shape of the pipe structure 12, and is preferably a frequency or wavelength of sound that forms a uniform and stable standing wave (i.e., a pattern) inside the pipe structure 12.

In the present invention, the position of the opening 24 of the sound-insulating structure such as the tubular body 14 is the position of the center of gravity of the opening 24, and the position of the radiation surface of the sound-insulating structure is the position of the center of gravity of the radiation surface.

The basis of the above formula (1) is based on the following principle.

This principle is explained in detail with reference to fig. 6.

As shown in fig. 6, in the sound insulation system 10 according to the present invention, when sound passes through the pipe structure 12 and a sound insulation structure such as the tubular body 14 exists inside the pipe structure 12, sound waves propagating through the pipe structure 12 are separated into sound entering the sound insulation structure such as the tubular body 14 and sound directly propagating through the pipe structure 12.

The sound entering the sound insulating structure side such as the tubular body 14 is again emitted from the tubular body 14 and returns to the inside of the tubular structure 12, and at this time, a finite phase difference θ 1 is given between the case of entering the tubular body 14 and the case of emitting the sound from the tubular body 14. For example, when the sound insulation structure is a tubular body 14 (tubular structure: structure such as a tube), a phase difference θ 1 depending on the back surface distance d of the tubular body 14 is given to sound by 2 π × 2d/λ. Here, as shown in fig. 6, the phase difference θ 1 can be referred to as a phase difference at a position Op of the opening 24 of the sound that enters the sound insulating structure such as the tubular body 14 from the opening 24 and is re-radiated from the opening 24. In addition, the position Op of the opening portion 24 is defined as the center of gravity position of the opening surface of the opening portion 24. The back surface length or the back surface distance d of the tubular body 14 is defined as a length from the center of gravity position of the opening surface of the opening 24, that is, the position Op of the opening 24 to the end of the tubular body 14.

On the other hand, the sound directly propagating through the tube structure 12 has, for example, a mode (independent standing wave) defined by the structure of the tube structure 12, or a maximum value or an antinode a and a minimum value or a node N of the sound pressure are formed by interference between the sound wave reflected from the open end 20 of the tube structure 12 and the sound wave propagating through the tube structure 12 toward the open end 20. In this case, the sound directly propagating through the pipe structure 12 returns again and passes through the sound insulating structure such as the tubular body 14 in the opposite direction. At this time, the phase difference θ 2 generated when the sound travels to and returns from the antinode a or the portion at which the sound reaches the maximum value of the standing wave (mode) is 2 pi × 2L/λ when the distance between the antinode a or the portion at which the sound reaches the maximum value of the standing wave (the position of the tube structure 12, for example, the position of the antinode a) and the opening 24 or the radiation surface of the sound insulating structure is L. Here, as shown in fig. 6, the phase difference θ 2 can be referred to as a phase difference of the sound returned to the position Op of the opening 24 without entering the sound insulating structure such as the tubular body 14.

In fig. 6, when a distance between the open end 20 of the pipe structure 12 and a position (for example, a position of an antinode a) in the pipe structure 12 at which the sound pressure is maximum is defined as Lx and a distance between the open end 20 of the pipe structure 12 and a position Op of the opening portion 24 of the tubular body 14 is defined as Lb, the distance L may be given as a difference between the distance Lb and the distance Lx (L ═ Lb-Lx). The distance L is half the distance to and from which sound propagates through the pipe structure 12.

In the present invention, the position of the pipe structure 12 where the sound pressure becomes the maximum value is preferably an antinode a of a standing wave of the sound formed by the pipe structure 12.

As will be described later, the tube structure 12 preferably has resonance, and satisfies the above formula (1) at a frequency fm at which resonance occurs.

When the phase difference between the sound that enters the sound insulating structure such as the tubular body 14 from the opening 24 and is emitted again from the opening 24 and the sound that directly propagates in the tube structure 12 and returns to the position Op of the opening 24 of the sound insulating structure such as the tubular body 14 is zero or smaller, that is, when the difference between the phase difference θ 1 and the phase difference θ 2 is zero or smaller, the amplitude of the sound that returns at the tube structure 12 becomes large, and therefore, the sound tends to remain inside the tube structure 12, and thus the transmission loss increases.

Here, the tubular body 14 is preferably a resonator, and satisfies the expression (1) above at a frequency different from the resonance frequency of the tubular body 14.

It is preferable that the transmission loss is maximized at a frequency of the sound wave satisfying the above expression (1).

When | θ 1 — θ 2|, is 0, the state in which the transmission loss is large becomes maximum, and the transmission loss gradually becomes smaller as deviating from this case.

On the other hand, if the value of | θ 1 — θ 2| exceeds pi/2, a stronger pipe coupling mode is less likely to be formed, transmission loss is reduced, and sound is amplified (sound is more likely to be emitted from the pipe structure) in some cases, as compared with the case where | θ 1 — θ 2|, is equal to 0. Therefore, the value of | θ 1- θ 2| is limited to be pi/2 or less (i.e., | θ 1- θ 2| ≦ pi/2).

(embodiment 2)

The present inventors have also found that the following requirements need to be satisfied in order to simultaneously exhibit the increase in the transmission loss in (i) and (ii).

In embodiment 2 of the present invention, when the sound insulating structure is the tubular body 14, the tubular body 14 has the resonance frequency fr [ Hz ]]Transmission loss in the tube structure 12Of the frequencies fm1, fm2, fm3, … … (refer to fig. 5) at which the transmission loss becomes minimum in the spectrum, the frequency of less than the resonance frequency fr is the maximum frequency fma Hz]In the above description, La1 represents a distance between the opening 24 of the tubular body 14 and a position Op of the pipe structure 12 closest to the opening 24 on the same side as the propagation direction of sound and having the maximum value of sound pressure (for example, an antinode a) at the frequency fma, and λ represents a wavelength at the frequency fma _fmaIn this case, the following formula (2) is required.

0≤La1≤λ _fma/4……(2)

The basis of the above formula (2) is based on the following principle.

This principle is explained in detail with reference to fig. 7.

In the sound insulation system shown in fig. 7, as described above, when the difference between the phase difference θ 1 of the sound entering the tubular body 14 from the opening 24 and radiated again from the opening 24 and the phase difference θ 2 of the sound directly propagating through the tubular body 12 and returning to the position (for example, the center position) Op of the opening 24 of the tubular body 14 is small while the sound of the sound source 26 propagates inside the tubular body 12, the sound tends to remain inside the tubular body 12, and the transmission loss increases.

In the present invention, when the number of the outlet-side open ends 20 is 1, the propagation direction of sound can be defined as a direction from the inside of the pipe structure 12 toward the open ends 20. When the number of pipe structures 12 is plural, and the sound source 26 such as a noise source is not present inside the pipe structures 12, the sound pressure can be measured by the measurement microphone 28 at the opening end surfaces of the plural pipe structures 12, and can be defined as a direction from the opening end surface having a large sound pressure (for example, the opening surface of the opening end 22 in the example shown in fig. 7) toward the end surface having a small sound pressure (for example, the opening surface of the opening end 20 in the example shown in fig. 7). When the sound source 26 of the noise source is inside the pipe structure 12 (see fig. 26 described later), it can be defined as a direction from the sound source 26 toward the open end 20 of the pipe structure 12.

Here, as shown in fig. 7, in the pipe structure 12When the transmitted sound is a sound of a frequency fma at which the transmission loss is the minimum value and which easily transmits through the pipe structure 12, the position (for example, the position of the antinode a) in the pipe structure 12 at which the sound pressure is the maximum value, at which the sound transmitted through the position Op of the opening 24 of the tubular body 14 is reflected toward the position Op of the opening 24, is positioned closer to the open end 20 of the pipe structure 12 than the position Op of the opening 24. On the other hand, the position (for example, the position of the node N) in the pipe structure 12 at which the sound pressure of the sound of the frequency fma propagating through the pipe structure 12 is the minimum value is the position of the pipe structure 14 closer to the open end 22 of the pipe structure 12 than the opening 24 of the pipe structure 14. Therefore, the distance La1 between the position Op of the opening portion 24 of the tubular body 14 and the position inside the pipe structure 12 where the sound pressure takes the maximum value (for example, the position of the antinode a) is λ 1 which is the distance between the position inside the pipe structure 12 where the sound pressure takes the maximum value (for example, the position of the antinode a) and the position inside the pipe structure 12 where the sound pressure takes the minimum value (for example, the position of the node N) _fmaAnd/4 or less.

That is, in the present embodiment, in order to improve the sound insulation effect of the sound at the frequency fma on the low frequency side of the resonance frequency fr, the distance La1 is defined to be 0 or more and λ 1 _fmaAnd/4 or less, and satisfies the above formula (2).

From the above, it is preferable that the position Op of the opening 24 of the tubular body 14 is located at a position different from the position of the node N (not the position of the node N).

As shown in fig. 7, the distance La1 is a half of the distance that sound propagating through the pipe structure 12 travels back and forth, and is given as the difference between the distance Lb and the distance Lx (L ═ Lb-Lx).

In the present embodiment, the reason why the distance La1 is limited to the above formula (2) is as follows.

First, since the frequency fma on the low frequency side is a frequency lower than the resonance frequency of the tubular body 14, the phase difference θ 1(═ 2d × 2 pi/λ) is set at the frequency fma _fma) Becomes smaller than pi. On the other hand, the phase difference θ 2 generated by the round-trip distance La1 is λ at the distance La1 _fmaAt time/4, it becomes pi (═ 2La 1X 2 pi/lambda _fma). Since θ 1 is smaller than π, La1 ≦ λ/4 is necessary to make the value of | θ 1- θ 2| close to 0.

In the present embodiment, when the length of the back surface (back surface distance) of the tubular body 14 is defined as d, the following formula (3) is preferably satisfied.

d＜λ _fma/4……(3)

The sound entering the tubular body 14 through the opening 24 and radiated again through the opening 24 travels back and forth by the back length d. Since the difference between the phase difference θ 1 by the distance d to and fro the sound entering the tubular body 14 and the phase difference θ 2 by the distance La1 to and fro the sound propagating through the pipe structure 12 is small, it can be said that the back length d of the tubular body 14 preferably satisfies the above expression (3) as long as La1 satisfies the above expression (2). This is why the back surface length d is limited to the above formula (3).

In the present embodiment, the opening 24 of the tubular body 14 is preferably provided at a distance λ from the open end 20 of the tube structure 12 _fmaInside the position.

When viewed from a position (for example, a position of an antinode a) inside the pipe structure 12 where the sound pressure is at a maximum, the open end 20 of the pipe structure 12 is located on a side close to a position (for example, a position of a node N) where the sound pressure is at a minimum, but does not reach the position. Therefore, the distance Lx between the open end 20 of the pipe structure 12 and the position (for example, the position of the antinode a) inside the pipe structure 12 where the sound pressure takes the maximum value is larger than λ _fmaAnd/2 is short. I.e., Lx < lambda _fma/2。

On the other hand, a distance Lb between the open end 20 of the pipe structure 12 and the position Op of the opening 24 of the tubular body 14 is given as the sum of the distance La1 and the distance Lx (Lb ═ La1+ Lx).

Therefore, Lb is La1+ Lx < λ _fma/4+λ _fma/2＝3λ _fma/4＜λ _fmaAnd is Lb < lambda _fma。

That is, the distance ratio λ between the open end 20 of the tubular structure 12 and the position Op of the opening 24 of the tubular body 14 _fmaShort. Therefore, it can be said that the opening 24 of the tubular body 14 is preferably provided at a distance λ from the open end 20 of the tube structure 12 _fmaInside the position. This is why.

(embodiment 3)

In embodiment 3 of the present invention, when the sound insulation structure is the tubular body 14, the tubular body 14 has a resonance frequency fr [ Hz ], and among frequencies fm1, fm2, fm3, … … (see fig. 5) at which the transmission loss becomes minimum in the transmission loss spectrum of the tubular structure 12, of frequencies higher than the resonance frequency fr, in the minimum frequency fmb [ Hz ], the distance between the opening 24 of the tubular body 14 and the position Op closest to the opening 24 on the side in the same direction as the propagation direction of sound at the frequency fmb and the position of the tubular structure 12 at which the sound pressure becomes the maximum value (for example, antinode a) is La2, and the wavelength at the frequency fmb is λ fmb, it is preferable that the following formula (4) is satisfied.

λ _fmb/4≤La2≤λ _fmb/2……(4)

The basis of the above formula (4) is based on the following principle.

This principle is explained in detail with reference to fig. 8.

In the sound insulation system shown in fig. 8, as described above, when the difference between the phase difference θ 1 of the sound entering the tubular body 14 from the opening 24 and radiated again from the opening 24 and the phase difference θ 2 of the sound directly propagating in the tubular body 12 and returning to the position (for example, the center position) Op of the opening 24 of the tubular body 14 is small while the sound of the sound source 26 propagates inside the tubular body 12, the sound tends to remain inside the tubular body 12, and the transmission loss increases.

Here, as shown in fig. 8, when the sound propagating through the pipe structure 12 is a sound of a frequency fmb that is easily transmitted through the pipe structure 12 (that is, transmission loss is the minimum), the position (for example, the position of the antinode a) in the pipe structure 12 at which the sound propagating through the position Op of the opening 24 of the tubular body 14 is reflected toward the position Op of the opening 24 (that is, sound pressure is the maximum) becomes a position closer to the open end 20 side of the pipe structure 12 than the position Op of the opening 24. On the other hand, the sound pressure of sound of frequency fmb propagating in the pipe structure 12 is minimizedThe position within the pipe structure 12 (for example, the position of the node N) is a position between the position Op of the opening 24 of the tubular body 14 and the position within the pipe structure 12 (for example, the position of the antinode a) at which the sound pressure takes the maximum value. Therefore, the distance La2 between the position Op of the opening portion 24 of the tubular body 14 and the position inside the pipe structure 12 where the sound pressure takes the maximum value (for example, the position of the antinode a) is λ 2 which is the distance between the position inside the pipe structure 12 where the sound pressure takes the maximum value (for example, the position of the antinode a) and the position inside the pipe structure 12 where the sound pressure takes the minimum value (for example, the position of the node N) _fmbMore than/4. Further, as shown in fig. 8, since the position in the pipe structure 12 where the sound pressure is the minimum (for example, the position of the node N) is closer to the position Op of the opening portion 24 of the tubular body 14 than the position in the pipe structure 12 where the sound pressure is the maximum (for example, the position of the antinode a), the distance La2 is λ _fmbAnd/2 or less.

That is, in the present embodiment, the distance La2 is defined as λ 2 in order to improve the sound insulation effect of sound at the frequency fmb on the higher frequency side than the resonance frequency fr _fmbA/4 or more and lambda _fmbAnd/2 or less, and satisfies the above formula (4).

As shown in fig. 8, the distance La2 is a half of the distance that sound propagating through the pipe structure 12 travels back and forth, and is given as the difference between the distance Lb and the distance Lx (L ═ Lb-Lx).

In the present embodiment, the reason why the distance La2 is limited to the above formula (4) is as follows.

First, since the frequency fmb on the high frequency side is a frequency higher than the resonance frequency of the tubular body 14, the phase difference θ 1(═ 2d × 2 pi/λ) at the frequency fmb is set to be a phase difference θ 1 _fmb) Becomes greater than pi. On the other hand, the phase difference θ 2 generated by the round-trip distance La2 is λ at La2 _fmbAt time/4, it becomes pi (═ 2La 2X 2 pi/lambda _fmb). Since θ 1 is larger than π, in order to make the value of | θ 1- θ 2| approach 0, θ 2 needs to be larger than π, and La2 ≧ λ/4 needs to be set.

On the other hand, if the distance La2 becomes larger than λ/2, the antinode of adjacent sound pressure is exceededAnd therefore the position of the maximum value of the sound pressure defined in the above is changed. Therefore, La2 defined hereinbefore becomes smaller than λ _fmbAnd/4 becomes unsuitable, so La 2. ltoreq. lambda/2 needs to be satisfied.

In the present embodiment, the opening 24 of the tubular body 14 is preferably provided at a position within a distance λ fmb from the open end 20 of the tube structure 12.

When viewed from a position (for example, a position of an antinode a) inside the pipe structure 12 where the sound pressure is at a maximum, the open end 20 of the pipe structure 12 is located on a side close to a position (for example, a position of a node) where the sound pressure is at a minimum, but does not reach the position. Therefore, the distance Lx between the open end 20 of the tube structure 12 and the position inside the tube structure 12 where the sound pressure takes the maximum value (for example, the position of the antinode a) is shorter than λ fmb/2. I.e., Lx < lambda _fmb/2。

On the other hand, a distance Lb between the open end 20 of the pipe structure 12 and the position Op of the opening 24 of the tubular body 14 is given as the sum of the distance La2 and the distance Lx (Lb ═ La2+ Lx).

Therefore, Lb is La2+ Lx < λ _fmb/2+λ _fma/2＝λ _fmbAnd is Lb < lambda _fmb。

That is, the distance from the open end 20 of the tube structure 12 to the position Op of the opening 24 of the tubular body 14 is shorter than λ fmb. Therefore, it can be said that the opening 24 of the tubular body 14 is preferably provided at a distance λ from the open end 20 of the tube structure 12 _fmbInside the position. This is why.

In addition, in

embodiments

2 and 3 of the present invention, it is also preferable that the opening 24 of the tubular body 14 is provided at a distance of the wavelength λ from the open end 20 of the tube structure 12, respectively _fmaAnd lambda _fmbBecause of the above, it can be said that also in embodiment 1 of the present invention, it is preferable that the opening 24 of the tubular body 14 is provided at a position within the wavelength λ from the open end 20 of the tube structure 12.

However, in

embodiments

2 and 3 of the present invention, the opening 24 of the tubular body 14 is preferably disposed at a position other than the node N, for example, at a position where the sound pressure has a minimum value. Here, not the bit of node NMeans that in addition to node N, a distance λ is set from node N _fmaA/8, or λ _fmbPosition around/8.

Fig. 9 is a graph showing the relationship between transmission loss and frequency of the sound insulation system 10 shown in fig. 1 in which the tubular body 14 shown in fig. 3 is disposed inside the straight tube portion 16 of the tube structure 12 shown in fig. 2 and on the bottom surface 16a of the straight tube portion 16.

As shown in the explanation of fig. 4A and 4B, the dimensions of the straight tube portion 16 and the bent portion 18 of the tube structure 12 shown in fig. 2 are as follows, and the dimensions of the tubular body 14 shown in fig. 3 are as follows, i.e., the back surface length d is 100mm, the height is 20mm, the width is 163mm, and the slit dimensions of the opening portion 24 are as follows, i.e., the slit width is 20mm and the slit length is 163 mm.

The tubular body 14 in the sound insulating system 10 shown in fig. 1 is disposed at a position Op of the opening portion 24 at a distance of 170mm from the open end 20 of the pipe structure 12. Namely, the distance Lb is 170 mm.

The sound emitted from the sound source 26 disposed at the open end 22 of the bent portion 18 of the pipe structure 12 and radiated from the open end 20 of the straight pipe portion 16 of the pipe structure 12 is measured by the microphone 28.

In this result, the resonance frequency fr of the tubular body 14 was 850Hz, and the maximum frequency fma on the low frequency side (fr > fma) was 600Hz and the maximum frequency fmb on the high frequency side (fr < fmb) was 1000Hz, out of the frequencies at which the transmission loss of the tube structure 12 became minimum. When the sound insulating structure such as the tubular body 14 has a resonance frequency fr [ Hz ], fr is preferably 1000Hz or less for realizing a small, low-frequency, and wide-band sound insulation.

Here, | θ 1- θ 2| at 600Hz is 0.66 (see example 3 described later) and is equal to or less than π/2, and | θ 1- θ 2| at 1000Hz is 0.92 (see example 8 described later) and is still equal to or less than π/2.

As a result, the above formula (1), which is a requirement of embodiment 1 of the present invention, is satisfied.

Therefore, as shown in fig. 9, in addition to 850Hz at the resonance frequency, a maximum value (peak value) of the transmission loss can be obtained in 600Hz, the pipe coupling mode can be obtained, and a maximum value (peak value) of the transmission loss can be obtained in 1000Hz, the pipe coupling mode can be obtained. That is, if | θ 1- θ 2| ≦ π/2 can be satisfied in a plurality of frequencies, the pipe coupling modes can be obtained simultaneously.

Further, the distance Lx at 600Hz was 100mm, and La1 was 70 mm. Wavelength lambda of 600Hz _fmaIs 575mm (═ 345X 10) ³/600)，

Thus, La1(═ 70mm) < lambda _fma/4(＝575/4＝144)。

As a result, it is found that the above formula (2), which is a requirement of embodiment 2 of the present invention, is also satisfied.

Further, the distance Lx at 1000Hz was 50mm, and La1 was 120 mm. Wavelength lambda of 1000Hz _fmaIs 345mm (═ 345X 10) ³/1000)，

Thus, it becomes λ _fma/4(＝345/4＝86)＜La1(＝120mm)＜λ _fma/2(＝345/2＝173)。

As a result, the above formula (3), which is a requirement of embodiment 3 of the present invention, is also satisfied.

In the present invention, the tube structure 12 has at least 1 open end 20, and may have any structure as long as it is in a tube shape, and it is a tube structure used for various purposes, and preferably has air permeability. Therefore, both ends of the pipe structure 12 are preferably open ends and both sides are open, but when one end of the pipe structure 12 is attached to a sound source, only the other end may be open and open ends may be provided.

The tube shape of the tube structure 12 may be a bent tube shape having a rectangular cross section as shown in fig. 2, and is not particularly limited. The tube structure 12 may be, for example, a straight tube shape as shown in fig. 25 or 26 described later, but it is preferable that the tube structure 12 is curved.

The pipe structure 12 may have a pipe shape as shown in fig. 43, 44, and 45, for example, which will be described later.

The sectional shape of the pipe structure 12 is also not particularly limited, and may be any shape. For example, the sectional shape of the tube structure 12 may be a regular polygon such as a square, a regular triangle, a regular pentagon, or a regular hexagon. The cross-sectional shape of the tube structure 12 may be a triangle including an isosceles triangle and a right triangle, a polygon including a rhombus and a parallelogram, a pentagon, or a hexagon, or may be an irregular shape. The sectional shape of the tube structure 12 may be circular or elliptical. The cross-sectional shape of the pipe structure 12 may be changed in the middle of the pipe structure 12.

Examples of the sound insulating structure such as the pipe structure 12 and the tubular body 14 include pipe structures such as pipes and silencers used by being directly or indirectly attached to industrial equipment, transportation equipment, general household equipment, and the like, and sound insulating structures such as the tubular body 14. Examples of industrial equipment include copying machines, blowers, air conditioners, ventilating fans, pumps, and generators, and various manufacturing equipment that generate sound, such as coaters, rotating machines, and conveyors. Examples of the transport equipment include automobiles, electric trains, and aircraft. Examples of general household appliances include refrigerators, washing machines, dryers, televisions, copiers, microwave ovens, game machines, air conditioners, fans, PCs, vacuum cleaners, and air cleaners. The pipe structure 12 includes, in particular, a pipe for building and construction materials, a pipe attached to an electronic device such as a muffler for an automobile, a copying machine, and the like. Further, a ventilation sleeve (a sleeve having a linear shape, a crankcase shape, or the like, but not limited thereto) used for building materials can be used.

In the above example, the tubular body 14 is used as the sound insulating structure of the present invention, but the present invention is not limited to this, and any sound insulating structure may be used and may be disposed at any position of the pipe structure 12 as long as the opening or the radiation surface of the sound insulating structure can be disposed in the pipe structure 12.

The sound insulating structure such as the tubular body 14 is preferably disposed inside the tube structure 12, and is preferably incorporated in the tube structure 12.

Further, a sound insulating structure such as a tubular body 14 may be integrally formed with the pipe structure 12.

The sound insulating structure such as the tubular body 14 may be detachable from the pipe structure 12.

For example, although not shown in the drawings, in the sound insulation system 10 shown in fig. 1, the sound insulation structure such as the tubular body 14 may be detachably fixed to the tubular body 12 by fixing magnets to at least a part of the outer surface of the bottom portion of the sound insulation structure such as the tubular body 14, fixing magnets having different polarities to at least a part of the corresponding positions on the inner surface of the bottom portion of the tubular body 12, and detachably fixing 1 group of magnets having different polarities to each other in close contact with each other. Alternatively, the sound insulating structure such as the tubular body 14 may be detachably fixed to the tube structure 12 by using a surface fastener such as MagicTape (registered trademark) (manufactured by Kuraray Fastening co., ltd.) or a double-sided tape instead of the 1 set of magnets, or both may be fixed by using a double-sided tape.

The sound insulation structure may be a structure in which a sound absorbing material such as glass wool is filled in at least a part of the inside of the tubular body 14, or a structure in which a sound absorbing material is provided on at least a part of the inner surface and/or the outer surface of the tubular body 14. That is, as the sound insulation structure, it is preferable that the sound absorbing material is provided at least in a part of the tubular body 14.

The sound absorbing material is not particularly limited, and conventionally known sound absorbing materials can be suitably used. For example, it is possible to utilize: foaming materials such as foamed polyurethane, flexible polyurethane foam, wood, ceramic particle sintered materials, phenolic foam, and the like, and materials containing minute air; fibers such as glass wool, rock wool, microfiber (for example, thin manufactured by 3M Company), floor mat, carpet, melt-blown nonwoven fabric, metal nonwoven fabric, polyester nonwoven fabric, metal wool, felt, soft fiber board, and glass nonwoven fabric, and nonwoven fabric-like materials; wood wool cement board; nanofiber-based materials such as silica nanofibers; a gypsum board; various known sound absorbing materials or porous sound absorbing materials.

The entire or one surface of the opening of the sound insulating structure may be covered with a sound absorbing material. For example, the opening surface of the opening of the sound insulating structure may be covered with a film penetrating several micrometers to several millimeters. Further, for example, a sound insulation structure in which the opening surface of the opening is covered with a metal film having fine through-holes with a through-hole diameter of about 0.1 to 50 μm, a thickness of about 1 to 50 μm, and an opening ratio of about 0.01 to 0.3 can be used.

The material of the sound insulation structure such as the tube structure 12 and the tubular body 14 is not particularly limited as long as it has appropriate strength for application to the sound insulation object and is resistant to the sound insulation environment of the sound insulation object, and can be selected according to the sound insulation object and the sound insulation environment thereof. Examples of the material of the sound-insulating structure such as the tube structure 12 and the tubular body 14 include metal materials such as aluminum, titanium, magnesium, tungsten, iron, steel, chromium molybdenum, nickel-chromium molybdenum, and alloys thereof, resin materials such as acrylic resin, polymethyl methacrylate, polycarbonate, polyamideimide, polyarylate, polyetherimide, polyacetal, polyether ether ketone, polyphenylene sulfide, polysulfone, polyethylene terephthalate, polybutylene terephthalate, polyimide, and triacetyl cellulose, Carbon Fiber Reinforced Plastics (CFRP), Carbon Fiber and Glass Fiber Reinforced Plastics (GFRP), and the like.

Further, a plurality of these materials may be used in combination.

The materials of the sound insulating structure such as the tube structure 12 and the tubular body 14 may be the same or different. When the sound insulating structure such as the tubular body 14 is integrally molded with the tube structure 12, the materials of the sound insulating structure such as the tube structure 12 and the tubular body 14 are preferably the same.

The method of disposing the sound insulating structure such as the tubular body 14 inside the pipe structure 12 is not particularly limited, and any conventionally known method may be used, including a case where the sound insulating structure such as the tubular body 14 is detachably disposed on the pipe structure 12.

In the sound insulation system of the present invention, as described above, the interior of the sound insulation structure may be filled with a conventionally known sound absorbing material such as glass wool.

Fig. 10 is a graph showing the simulation results when the inside of the tubular body 14 of the sound insulating system 10 shown in fig. 1 is filled with glass wool and when it is not filled, and showing the relationship between the transmission loss and the frequency of the sound insulating system 10.

In the acoustic insulation system 10 shown in fig. 1, a COMSOL MultiPhysics ver5.3a acoustic module is used, while assuming that the inside of the tubular body 14 is filled with glass wool (propagation resistance 20000 Pas/m) ²) Penetration when full and when not fullThe loss on fire was simulated. The results are shown in FIG. 10.

In the example shown in fig. 10, the pipe structure 12 and the tubular body 14 having the above dimensions are used except that the distance Lb from the open end 20 of the pipe structure 12 to the position Op of the opening 24 in the tubular body 14 is 185 mm.

In the example shown in FIG. 10, the value of | θ 1- θ 2| at 600Hz is 0.33 and is equal to or less than π/2, and the value of | θ 1- θ 2| at 1000Hz is 1.28 and is still equal to or less than π/2.

As shown in fig. 10, when the tubular body 14 is filled with glass wool, pipe coupling occurs at either 600Hz or 1000Hz, and even at 600Hz, 1000Hz, and 850Hz, which is the resonance frequency fr of the tubular body 14, the transmission loss is lower than when the tubular body 14 is not filled with glass wool. However, when the tubular body 14 is filled with glass wool, the transmission loss can be enlarged in the vicinity of the frequencies 600Hz and 1000Hz at which the pipe coupling occurs, and in the region exceeding 1000Hz (for example, the region of 1000Hz to 1400 Hz).

From the above, it is understood that, according to the calculation results, even when the glass wool is filled, the transmission loss can be obtained in a relatively wide frequency band in (600Hz, 1000 Hz).

A sound insulation system in which a sound absorbing material is provided on at least a part of the inner surface and/or the outer surface of a sound insulation structure will be described later.

Further, as in sound insulation system 10a shown in fig. 11, a sound insulation structure such as tubular body 14 may be disposed in pipe structure 12 so that the position of opening 24 is in the opposite direction to that shown in fig. 1.

Fig. 12 is a graph showing the relationship between the transmission loss and the frequency of the sound insulation system 10, except that the length d of the back surface of the tubular body 14 is set to 112mm in the sound insulation system 10 shown in fig. 1, and the above-described dimensions are used.

Fig. 13 is a graph showing the relationship between the transmission loss and the frequency of the sound insulation system 10a, except that the length d of the back surface of the tubular body 14 in the sound insulation system 10a shown in fig. 11 is set to 112mm and the above dimensions are used.

As shown in fig. 12 and 13, since the resonance frequency fr of the tubular body 14 is 750Hz and the distance Lb is 170mm, the values of | θ 1 to θ 2| at 600Hz are all 0.92, and the above formula (1) is satisfied.

As shown in fig. 12 and 13, it can be seen that the conditions of the present invention are satisfied regardless of the direction of the tubular body 14, a high transmission loss can be obtained in 600Hz at which the pipe coupling occurs, and the direction of the tubular body 14 may be any direction.

Further, as the sound insulation system 10b shown in fig. 14, a tubular body 30 having an opening 24 at the center may be disposed in the pipe structure 12 as the sound insulation structure. Here, the above-described dimensions of the sound insulation system 10 shown in fig. 1 were used except that the length d of the back surface of the tubular body 30 was set to 200 mm. In this configuration, since the resonance frequency fr of the tubular body 30 is 750Hz and the distance Lb is also 170mm, the value of | θ 1- θ 2| at 600Hz is 0.66, and the value of | θ 1- θ 2| at 1000Hz is 0.92, satisfying the above equation (1). The size of the opening 24 of the tubular body 30 is 20 mm.

Fig. 15 shows the simulation result of the sound insulation system 10b shown in fig. 14, which is a graph showing the relationship between the transmission loss and the frequency of the two.

As shown in fig. 15, the condition of the present invention is satisfied even when the tubular body 30 having the opening 24 at the center is disposed in the pipe structure 12. Therefore, it is found that a high transmission loss can be obtained even at the resonance frequency fr of the tubular body 30, i.e., 750Hz, and that a high transmission loss can be obtained even at 600Hz and 1000Hz by generating the pipe coupling.

As shown in fig. 16, in the sound insulation system 10c, a tubular body 32 having an opening 24 may be disposed in the tube structure 12 at the end portion on the open end 20 side of the tube structure 12 on the right side in fig. 16 as a sound insulation structure. Here, the above-described dimensions of the sound insulation system 10 shown in fig. 1 are used in addition to the opening 24 of the tubular body 32 being provided at the right-hand side end portion of the tubular body 32 in fig. 16. Instead of the tubular body 32 having the opening 24, a sound insulation structure having a radiation surface at the end of the tube structure 12 on the open end 20 side may be used.

In this configuration, the resonance frequency fr of the cylindrical body 32 is 750Hz, the length d of the back surface of the cylindrical body 32 is 100mm, and the distance Lb is also 170 mm. Therefore, the value of | θ 1- θ 2| at 600Hz is 0.66, and the value of | θ 1- θ 2| at 1000Hz is 0.92, satisfying the above equation (1).

Fig. 17 shows the simulation result of the sound insulation system 10c shown in fig. 16, which is a graph showing the relationship between the transmission loss and the frequency.

As shown in fig. 17, the conditions of the present invention are satisfied even when the tubular body 32 having the opening 24 is disposed in the tube structure 12 at the end portion on the open end 20 side of the tube structure 12. Therefore, it is found that a high transmission loss can be obtained even at 750Hz, which is the resonance frequency fr of the tubular body 32, and that a high transmission loss can be obtained even at 600Hz and 1000Hz by generating the pipe coupling mode. That is, it is known that by developing the pipe coupling mode, the transmission loss in a wide band can be obtained in conjunction with the air column resonance.

In the sound insulation system of the present invention, a plurality of sound insulation structures such as a plurality of tubular bodies may be used. That is, it is preferable that the number of the tubular bodies 14 as the sound insulation structure disposed inside the tube structure 12 is 2 or more.

For example, as shown in fig. 18, in the

sound insulation system

10f, 2

tubular bodies

14a and 14b having different lengths (back surface distances d) may be disposed in the pipe structure 12 as a sound insulation structure. Here, in the sound insulation system 10f shown in fig. 18, the tubular body 14a is the tubular body 14 shown in fig. 1, and the opening portion 24a is located on the side of the open end 20 of the tubular structure 12, and the tubular body 14b is the tubular body 14 shown in fig. 11, and the opening portion 24b is located on the side opposite to the open end 20 of the tubular structure 12.

Fig. 19 is a graph showing the relationship between the transmission loss and the frequency of the sound insulation system 10f, in addition to the fact that the 2

tubular bodies

14a and 14b are arranged at the respective positions in the pipe structure 12 in the sound insulation system 10 shown in fig. 1, and the above-described dimensions are used. In the case of the graph shown in fig. 19, in the sound insulation system 10f shown in fig. 18, the length d of the back surface of the tubular body 14a is 100mm, the opening width of the opening 24a is 20mm, and the distance from the opening end 20 of the tube structure 12 to the position of the center of gravity of the opening 24a of the tubular body 14a is 185 mm. The length d of the back surface of the tubular body 14b was 112mm, the opening width of the opening 24b was 20mm, and the distance from the opening end 20 of the tube structure 12 to the position of the center of gravity of the opening 24b of the tubular body 14b was 130 mm.

In the tubular body 14a, as shown in fig. 19, a transmission loss due to air column resonance appears at 850 Hz.

Further, in 600Hz, the value of | θ 1 — θ 2|, is 0.33[ rad ], and the transmission loss due to the pipe coupling mode appears.

Further, in 1000Hz, the value of | θ 1 — θ 2|, is 1.28[ rad ], and a transmission loss due to the pipe coupling mode appears.

In the tubular body 14b, as shown in fig. 19, a transmission loss due to air column resonance also appears in 750 Hz.

Further, | θ 1- θ 2|, 1.17[ rad ] appears at 1000Hz, and the transmission loss due to the pipe coupling mode appears.

As described above, it is understood that transmission loss appears in a plurality of frequency bands by simultaneously utilizing resonance and pipe coupling of a plurality of tubular bodies, and thus high transmission loss exceeding 5dB can be obtained in a wide frequency range of 550Hz to 1000 Hz.

In this way, when the number of the sound insulation structures arranged in the pipe structure is 2 or more, the sound insulation effect is enhanced.

In the present invention, as shown in fig. 20, the sound insulation structure may be a helmholtz resonator 34. That is, as in the sound insulation system 10d shown in fig. 20, instead of the tubular body 14 shown in fig. 1, 1 or more helmholtz resonators 34 having the openings 36 may be arranged inside the pipe structure 12.

In the sound insulation system 10d shown in fig. 21, 4 helmholtz resonators 34 are arranged on the bottom surface 16a inside the straight tube portion 16 of the tube structure 12 shown in fig. 20. As shown in fig. 21, the widths of the 4 helmholtz resonators 34 coincide with the lateral width of the straight tube portion 16 of the tube structure 12.

As shown in fig. 22, in the case of the sound insulation system 10d using the helmholtz resonator 34, as in the case of the tubular body 14 of the sound insulation system 10 shown in fig. 6, when sound passes through the pipe structure 12, sound waves propagating in the pipe structure 12 are separated into sound entering the sound insulation structure, i.e., the helmholtz resonator 34, and sound directly propagating in the pipe structure 12.

The sound entering the helmholtz resonator 34 is again emitted from the helmholtz resonator 34 and returned to the inside of the pipe structure 12, and at this time, a finite phase difference θ 1 is given to the case of entering the helmholtz resonator 34 and the case of emitting the sound from the helmholtz resonator 34.

Here, the phase difference θ 1 of the sound re-radiated from the helmholtz resonator 34 can be obtained as follows with reference to the mechanical acoustics (CORONA) P69.

Phase difference θ 1 ═ arg (r)

Here, r is represented as follows. (C1.)

r＝CρcS _c/(2ZS+ρcS _c)

The acoustic impedance Z of the helmholtz resonator 34 (the real part is omitted for simplicity) can be expressed by the following equation.

Z＝jωρl _c+ρc ²S _c/(jωV _c)

Where ρ is the density of air, c is the speed of sound of air, l _cThe length (l) of the opening 36 of the Helmholtz resonator 34 corrected for the open end _cL +1.7r), l being the length of the opening 36, r being the radius of the opening 36, S _cIs the opening area (S) of the opening 36 _c＝πr ²)，V _cIs the internal volume of the helmholtz resonator 34 and S is 1/4 of the cross-sectional area of the tube structure 12 and the cross-sectional area of the helmholtz resonator 34.

Here, in the 1 helmholtz resonator 34, the internal space size is 40mm (length) × 40mm (width) × 20mm (height), the opening diameter of the opening 36 is 8mm, the plate thickness of the top plate provided with the opening 36 (the length of the opening 36) is 5mm, and the other plate thicknesses are 1 mm. And ρ is 1.205[ kg/m [ ] ²]、c＝343[m/S]、l＝5[mm]、r＝4[mm]、V _c＝0.04×0.04×0.02[m ³]。

In this case, θ 1 was 4.8[ rad ] at 1000 Hz.

On the other hand, as shown in fig. 22, the sound directly propagating through the pipe structure 12 has a mode (independent standing wave) defined by the structure of the pipe structure 12, or a maximum value, an antinode a, a minimum value, or a node N of the sound pressure is formed by interference between the sound wave reflected from the opening 36 of the helmholtz resonator 34 and the sound wave emitted from the opening 36, as in the case of the sound insulation system 10 shown in fig. 6. In this case, the sound directly propagating through the pipe structure 12 returns again and passes through the sound insulating structure such as the tubular body 14 in the opposite direction. At this time, the phase difference θ 2 generated when the sound travels to and returns from the antinode a or the portion at which the sound reaches the maximum value of the standing wave (mode) is 2 τ × 2L/λ (═ kL) when the distance between the antinode a or the portion at which the sound reaches the maximum value of the standing wave (position of the tube structure 12, for example, the position of the antinode a) and the center of gravity position of the opening 36 of the helmholtz resonator 34 is L. Here, as shown in fig. 22, the phase difference θ 2 can be referred to as a phase difference of sound that returns to the center of gravity of the opening 36 without entering the helmholtz resonator 34.

Fig. 23 is a graph showing transmission loss of absolute values | θ 1- θ 2| with respect to the difference in phase difference in 1000Hz in the sound insulation system 10d shown in fig. 21.

As is clear from FIG. 23, in the case of | θ 1- θ 2| ≦ π/2 in the above formula (1), a substantially high transmission loss appears. That is, it is known that the pipe coupling mode by the helmholtz resonator 34 appears at 1000 Hz.

Fig. 24 is a graph showing a transmission loss spectrum at a frequency when the distance L between the open end 20 of the tube structure 12 and the center of gravity of the opening 36 of the helmholtz resonator 34 is changed from 14cm to 20cm at 2cm intervals.

As is clear from fig. 24, in the sound insulation system 10d using the helmholtz resonator 34 as the sound insulation structure, in addition to the resonance frequency (near 650 Hz), the transmission loss due to the pipe coupling occurs also in the vicinity of 1000 Hz.

In the present invention, a film resonator, which is a structure composed of a film and a closed back space, is used as the sound insulation structure.

The helmholtz resonator 34 and the film resonator used in the present invention are not particularly limited, and may be any of the helmholtz resonators and film resonators known in the art.

In the present invention, as the sound insulation system 10e shown in fig. 25, a straight pipe structure 12a can be used as the pipe structure. In the sound insulation system 10e of the present invention, by disposing the sound insulation structure such as the tubular body 14 at an appropriate position on the bottom surface inside the linear tube structure 12a, the peak value of the transmission loss due to the air column resonance and the peak value of the transmission loss due to the pipe coupling mode can be exhibited similarly to the sound insulation system 10 shown in fig. 1.

In the present invention, as shown in fig. 26, the sound insulation system 10g may be configured such that a linear pipe structure 12b is used as the pipe structure, the right end in fig. 26 is an open end 20, the other end is a closed end 38, and a sound source (speaker) 26 is disposed inside the closed end 38 side of the pipe structure 12 b. In the sound insulation system 10g of the present invention, by disposing the sound insulation structure such as the tubular body 14 at an appropriate position on the bottom surface inside the linear pipe structure 12b, the peak value of the transmission loss due to the air column resonance and the peak value of the transmission loss due to the pipe coupling mode can be exhibited similarly to the sound insulation system 10 shown in fig. 1.

The film resonator may be any film resonator having: a frame having a hole portion therethrough; a film which is fixed to the frame so as to cover one opening surface of the hole and can vibrate; and a back member fixed to the frame so as to cover the other opening surface of the hole. Further, the diaphragm may have 1 or more holes formed therein, or may have 1 or more spindles. In the sound insulation system using the film resonator, the number of the film resonators to be used may be 1 or more.

The frame is formed to surround the penetrating hole portion in a ring shape, and is used for fixing and supporting the film so as to cover one surface of the hole portion, and serves as a node of film vibration of the film fixed to the frame. Therefore, the frame has higher rigidity than the film, and more specifically, both the mass per unit area and the rigidity are preferably high. In addition, the frame and the membrane may be integrated from the same material or different materials.

In addition, at least a part of the film needs to be fixed to the end of the hole of the frame. For sound absorption in the low frequency region, it is preferable that the entire end of the film is fixed to the frame.

The shape of the frame and the hole is not particularly limited, and may be, for example, a square, a rectangle, another quadrangle such as a rhombus or a parallelogram, a triangle such as a regular triangle, an equilateral triangle or a right-angled triangle, a polygon including a regular polygon such as a regular pentagon or a regular hexagon, a circle, an ellipse, or the like, or may be an irregular shape. The shape of the frame is preferably the same as the shape of the hole, but may be different.

The material of the frame is not particularly limited as long as it can support the film, has suitable strength for the sound insulation object, and has resistance to the sound insulation environment of the sound insulation object, and can be selected according to the sound insulation object and the sound insulation environment thereof. For example, the material of the frame may be a resin material or an inorganic material. Specific examples of the resin material include: acetyl cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate; olefin resins such as PolyEthylene (PE), polymethylpentene, cycloolefin polymers, and cycloolefin copolymers; acrylic resins such as polymethyl methacrylate, and polycarbonates. Further, resin materials such as polyimide, polyamideimide, polyarylate, polyetherimide, polyacetal, polyetheretherketone, polyphenylene sulfide, polysulfone, polybutylene terephthalate, and triacetyl cellulose can be cited. Further, Carbon Fiber-Reinforced Plastics (CFRP), Carbon Fiber-Glass-Reinforced Plastics (GFRP), and the like can be mentioned.

On the other hand, specific examples of the inorganic material include: glasses such as soda glass, potassium glass, lead glass, and the like; ceramics such as light-transmitting piezoelectric ceramics (PLZT: La-modified lead zirconate titanate); quartz; fluorite, and the like. Further, a metal material such as aluminum or stainless steel may be used. Further, a metal material such as titanium, magnesium, tungsten, iron, steel, chromium molybdenum, nickel chromium molybdenum, or an alloy thereof may be used.

Further, these plural materials may be used in combination as the material of the frame.

The back member closes a back space of the film surrounded by the inner peripheral surface of the frame.

The back member is a plate-like member that faces the film and is attached to the other end of the hole of the frame so that a back space formed by the frame on the back surface of the film is a closed space. The plate-like member is not particularly limited as long as it can form a closed space on the back surface of the film, and is preferably a plate-like member made of a material having higher rigidity than the film, and may be the same material as the film. When the films are fixed to the openings on both sides of the hole of the frame, the films on both sides may be formed with protrusions, or a spindle may be attached.

Here, as the material of the back surface member, for example, the same material as that of the frame can be used. The method of fixing the back member to the frame is not particularly limited as long as a closed space can be formed on the back surface of the film, and the same method as the above-described method of fixing the film to the frame may be used.

The back member is a plate-like member for closing a space formed by the frame on the back surface of the film, and therefore, may be integrated with the frame or may be integrally formed of the same material.

The peripheral portion of the film is fixed so as to be pressed against the frame in such a manner as to cover the hole portion inside the frame.

When the material of the film is a film-like material or a foil-like material, it is necessary to have strength suitable for the sound insulation object and resistance to the sound insulation environment of the sound insulation object. In addition, in order to allow the membrane to absorb or reflect the energy of sound waves to perform sound insulation, the material of the membrane needs to be capable of membrane vibration. The material of the film is not particularly limited as long as it has the above-described characteristics, and can be selected according to the sound insulation object, the sound insulation environment thereof, and the like.

Examples of the material of the film include resin materials that can be formed into a film such as polyethylene terephthalate (PET), polyimide, polymethyl methacrylate, polycarbonate, acrylic acid (polymethyl methacrylate), polyamideimide, polyarylate, polyetherimide, polyacetal, polyether ether ketone, polyphenylene sulfide, polysulfone, polybutylene terephthalate, triacetyl cellulose, polyvinylidene chloride, low-density polyethylene, high-density polyethylene, aromatic polyamide, silicone resin, ethylene ethyl acrylate, vinyl acetate copolymer, polyethylene, chlorinated polyethylene, polyvinyl chloride, polymethylpentene, and polybutylene. Further, metal materials that can be formed into a foil shape, such as aluminum, chromium, titanium, stainless steel, nickel, tin, niobium, tantalum, molybdenum, zirconium, gold, silver, platinum, palladium, iron, copper, and permalloy, can be cited. Further, other materials that can be formed into a fibrous film such as paper and cellulose, a nonwoven fabric, a thin film including nano-sized fibers, a porous material such as thin polyurethane and dilute sulfate processed into a thin film, a carbon material processed into a thin film structure, and the like can be mentioned.

The film is fixed to the frame so as to cover at least one opening of the hole of the frame. That is, the film may be fixed to the frame so as to cover the opening on one side or the other side or both sides of the hole portion of the frame.

The method of fixing the membrane to the frame is not particularly limited, and any method may be used as long as the membrane can be fixed to the frame so as to be a node of the membrane vibration. For example, a method of fixing the film to the frame includes a method using an adhesive, a method using a physical fastener, and the like.

In the method using an adhesive, the adhesive is applied to the surface of the hole surrounding the frame, the film is placed thereon, and the film is fixed to the frame with the adhesive. Examples of the adhesive include epoxy-based adhesives (e.g., Araldite (registered trademark) (manufactured by nichain co., ltd.), etc.), cyanoacrylate-based adhesives (e.g., Aron Alpha (registered trademark) (manufactured by toagoseico., ltd.), etc.), acrylic adhesives, and the like.

As a method of using a physical fastener, there is a method of sandwiching a film disposed so as to cover a hole portion of a frame between the frame and a fixing member such as a rod, and fixing the fixing member to the frame using a fastener such as a screw or a bolt.

The frame and the film may be separately formed and the film may be fixed to the frame, or the film and the frame formed of the same material may be integrated.

The sound insulation system of the present invention configured as described above can obtain transmission loss in a wide frequency band by simultaneously utilizing resonance and pipe coupling modes. That is, the sound insulation structure of the present invention can achieve a wider sound insulation effect.

In the present invention, a gas column resonator tube such as the tubular body 14 is preferably used as the sound insulation structure, but the sound insulation structure formed of the gas column resonator tube such as the tubular body 14 has the opening 24 and the closed space, and is configured as a gas column tube.

It is generally known that such a sound-insulating structure such as an air column resonance tube causes an air column resonance phenomenon. When a sound insulating structure such as a gas column resonance tube is provided in the tube structure according to the sound insulating system of the present invention, the transmission loss of the tube structure including the sound insulating structure increases at the resonance frequency.

Therefore, in the present invention, the sound insulating structure is preferably a sound insulating structure that causes a resonance phenomenon, for example.

As described above, it is natural that the helmholtz resonator and the film resonator may be used as a sound insulation structure for causing a resonance phenomenon, in addition to the air column resonator.

In the sound insulation system according to the present invention, in order to increase the transmission loss of the pipe structure over a wide frequency band based on the pipe coupling mode and the principle of resonance, it is preferable that both the air column resonance frequency and the pipe coupling mode are simultaneously exhibited. This can cause 2 or more transmission loss increases according to different principles, such as (i) an increase in transmission loss due to air column resonance and (ii) an increase in transmission loss due to the pipe coupling mode, and as a result, a broadband transmission loss can be obtained. The technique of the sound insulation system of the present invention for exhibiting not only the transmission loss due to resonance but also the transmission loss due to non-resonance can be said to be a technique which is not easily achieved by the conventional technique.

The sound insulation system of the present invention can obtain a peak value of non-resonant transmission loss based on the pipe coupling mode by optimizing the pipe structure and the arrangement of the sound insulation structure in the pipe structure. In particular, the sound insulation structure can be made smaller than the resonator by using the pipe coupling mode. Further, as described above, by using the pipe coupling mode and the resonance at the same time, the transmission loss can be obtained in a wide frequency band.

The sound insulating system according to the present invention may be a single sound insulating system including a single pipe structure and a sound insulating structure in the single pipe structure, or may be a sound insulating system including a plurality of single sound insulating systems, including a plurality of pipe structures and a sound insulating structure in the plurality of pipe structures, instead of the single sound insulating system.

In the sound insulation system including a plurality of single sound insulation systems, as described above, the characteristic is that the transmission loss peak of resonance and non-resonance is exhibited at the same time by appropriately setting the natural mode of the pipe structure, the position of the opening, and the length of the back surface of the sound insulation structure, and the transmission loss in a wide frequency band can be realized without using a sound absorbing material, and the application possibility is wide and high.

In the sound insulation system according to the present invention, as described above, the sound absorbing material may be provided inside the pipe structure or may be provided on at least a part of the surface inside and/or outside the sound insulation structure in order to further widen the transmission loss in a wide frequency band without using the sound absorbing material. That is, it is more preferable that the sound absorbing material is provided inside the pipe structure, and it is preferable that the sound absorbing material is provided at least in part of the sound insulation structure.

For example, as in the sound insulation system 10h shown in fig. 32, in the sound insulation system 10f shown in fig. 18, a sound absorbing material 40 such as urethane may be attached and provided to the inner upper surface (ceiling) of the pipe structure 12 with an adhesive, double-sided tape, or the like. As the sound absorbing material 40, the conventionally known sound absorbing material described above can be used.

In the sound insulation system 10h shown in fig. 32, the sound absorbing material 40 is preferably provided on the entire inner upper surface of the pipe structure 12, but may be provided on a part thereof. In addition, in sound insulation system 10h shown in fig. 32, sound absorbing material 40 is provided on the inner upper surface of pipe structure 12, but the present invention is not limited to this, and may be provided on another surface or a plurality of surfaces as long as it is inside pipe structure 12. In addition, when the sound absorbing material 40 is provided on the other surface, it is sufficient if it is provided at least partially. Of course, the sound absorbing material 40 may be provided in at least a part of the

tubular bodies

14a and 14b, which are sound insulation structures located inside the pipe structure 12.

Fig. 33 is a graph showing the relationship between transmission loss and frequency of the sound insulation system 10h shown in fig. 32, except that the sound absorbing material 40 is provided on the inner upper surface of the pipe structure 12 in the sound insulation system 10f shown in fig. 18, and the above dimensions are used. In the case of the graph shown in fig. 33, the sound absorbing material 40 is made of polyurethane, and the size thereof is 163mm × 394mm, which is the same as the size of the ceiling of the pipe structure 12. And the thickness was 10 mm.

In the sound insulation system 10h shown in fig. 32, by providing the sound absorbing material 40 inside the pipe structure 12, sound of a higher frequency (for example, a frequency exceeding 2 kHz) can be insulated in a very wide frequency band (exceeding 2kHz to 10kHz) in addition to the excellent sound insulation effect in a wide frequency band (for example, a frequency of 2kHz or less) including a low frequency band described above. Therefore, sound insulation for a large part of the audible range can be handled in addition to sound insulation for low frequency sounds of the present invention.

In addition, in the sound insulation system 10h shown in fig. 32, 2 sound insulation structures having the

tubular bodies

14a and 14b are provided in the pipe structure 12, but the present invention is not limited to this, and 1 tubular body may be provided, or 3 or more tubular bodies may be provided.

In the sound insulation system 10h shown in fig. 32, the sound absorbing material 40 is attached and provided on the inner upper surface of the pipe structure 12, but as in the sound insulation system 10i shown in fig. 34, the sound absorbing material 40 may be replaced by providing a replacement mechanism 44 for replacing the sound absorbing material replacement member 42 provided with the sound absorbing material 40 shown in fig. 35 on the inner upper surface of the pipe structure 12.

As shown in fig. 35, the sound absorbing material replacement member 42 is formed by attaching and fixing the sound absorbing material 40 to one surface of an intermediate member 46 such as a plate material by using an adhesive 48 such as an adhesive or a double-sided tape. Here, the intermediate member 46 may be any material as long as it can support the sound absorbing material 40, and can be inserted into and removed from the replacement mechanism 44 on the inner upper surface of the pipe structure 12, thereby enabling replacement (attachment and detachment) of the sound absorbing material 40.

The replacing mechanism 44 provided on the inner upper surface of the pipe structure 12 may be any mechanism capable of inserting and extracting the sound absorbing material replacing member 42 so that the sound absorbing material 40 side is positioned on the inner side (i.e., the lower side in fig. 34) of the pipe structure 12, and may be a mechanism having a mesh-like support member for supporting the surface of the sound absorbing material replacing member 42 on the sound absorbing material 40 side, a support frame for supporting the opposite ends of the sound absorbing material replacing member 42, or the like. The replacing mechanism 44 may further include rails, guides, and the like for guiding the intermediate member 46 (preferably, both ends of the intermediate member 46) of the sound absorbing material 40 to which the sound absorbing material replacing member 42 is not attached.

In the sound insulation system according to the present invention, as described above, the sound absorbing material may be provided on at least a part of the surface of the inside and/or outside of the sound insulation structure disposed inside the pipe structure.

For example, as in sound insulation system 10j shown in fig. 36, sound absorbing material 50 such as urethane may be attached and installed on the outer upper surfaces of 2

tubular bodies

14a and 14b, which are sound insulation structures disposed inside pipe structure 12, using an adhesive, double-sided tape, or the like, in sound insulation system 10f shown in fig. 18. In particular, when the sound insulation structure, i.e., 2

tubular bodies

14a and 14b, is assembled inside the pipe structure 12 in the later stage, as in the sound insulation system 10j shown in fig. 36, a sound absorbing material 50 such as urethane may be integrated with the sound insulation structure (the

tubular bodies

14a and 14 b). In particular, when the sound insulating structure can be attached (replaced), it is preferable to integrate the sound insulating structure with the sound absorbing material. Thus, it is not necessary to separately provide the sound absorbing material 50 such as urethane to the sound insulation structure (the

tubular bodies

14a and 14b) disposed in the pipe structure 12, and it does not take much time to provide the sound absorbing material 50. As the sound absorbing material 50, the conventionally known sound absorbing material described above can be used.

In sound insulation system 10j shown in fig. 36, sound absorbing material 50 is preferably provided on the entire outer upper surfaces of 2

tubular bodies

14a and 14b, respectively, but may be provided on a part thereof. For example, one of the 2

tubular members

14a and 14b may be provided over the entire outer upper surface and the other may be provided in a part thereof, both may be provided in a part thereof, or only one of the tubular members may be provided.

In addition, in the sound insulation system 10j shown in fig. 36, the sound absorbing material 50 is provided on the entire outer upper surfaces of the 2

tubular bodies

14a and 14b, respectively, but the present invention is not limited to this, and may be provided on at least a part of the surface inside and/or outside at least one of the 2

tubular bodies

14a and 14b, which is the sound insulation structure.

Fig. 37 is a graph showing the relationship between the transmission loss and the frequency of the sound insulation system 10j shown in fig. 36, except that the sound absorbing material 50 is provided on the outer upper surface of each of the 2

tubular bodies

14a and 14b in the sound insulation system 10j shown in fig. 18, and the above dimensions are used. In the case of the graph shown in fig. 37, the sound absorbing material 50 is made of polyurethane, and the size thereof is 163mm × 100mm, which is the same as the size of the outer upper surface of the 2

tubular bodies

14a and 14 b. And the thickness was 10 mm.

In the sound insulation system 10j shown in fig. 36, by providing the sound absorbing materials 50 on the outer upper surfaces of the 2

tubular bodies

14a and 14b, which are the sound insulation structures, respectively, it is possible to insulate sounds of higher frequencies (for example, frequencies exceeding 2 kHz) in a wider frequency band (exceeding 2kHz to 10kHz) in addition to the excellent sound insulation effect in a wide frequency band (for example, frequencies below 2 kHz) including a low frequency band, as in the case of the sound insulation system 10h shown in fig. 32, which has been described above. Therefore, sound insulation for a large part of the audible range can be handled in addition to sound insulation for low frequency sounds of the present invention.

Further, in the sound insulation system according to the present invention, it is preferable that the sound insulation characteristics of the sound insulation structure disposed inside the pipe structure (for example, the phase difference of the sound entering the sound insulation structure) be adjustable.

For example, as shown in fig. 38, the sound insulation system 10k may be configured such that the cover 56 having the opening 54 of the helmholtz resonator 52, which is a sound insulation structure disposed in the pipe structure 12, can be replaced (attached and detached) to and from the housing 58. In addition, the helmholtz resonator 52 of the sound insulation system 10k shown in fig. 38 is provided as a cover that can be replaced (detachably) with the opening 36 of the helmholtz resonator 34 of the sound insulation system 10d shown in fig. 20.

As shown in fig. 38, the helmholtz resonator 52 may be configured by attaching and fixing magnets 60a to the top edges of the four-sided side plates of the open face of the rectangular or cubic frame 58 having one open face, attaching and fixing magnets 60b having different polarities to positions corresponding to the top edges of the four-sided shape of the frame 58 of the four-sided cover 56 having the opening 54, and airtightly and detachably fixing 1 set of

magnets

60a and 60b having different polarities to each other. Alternatively, instead of the group 1

magnets

60a and 60b, as shown in fig. 39, the helmholtz resonator 64 may be configured by screwing the cover 56 to a rectangular side plate of the housing 58 with screws 62, and airtightly adhering and fixing the cover in a detachable manner. In addition, in the

helmholtz resonators

52 and 64, it is preferable that the portions of the housing 58 that are fixed in close contact with the rectangular side plates of the housing 56 be hermetically sealed in advance.

By thus making the cover 56 having the opening 54 replaceable, the

helmholtz resonators

52 or 64 having different sizes of the opening 54 can be configured, and the sound insulation characteristics (phase difference of sound entering the helmholtz resonators 52 or 64) can be adjusted.

For example, as shown in fig. 40, the sound insulation system 10l may be configured such that, for example, a tubular body (air column resonator) 66, which is a sound insulation structure disposed in the pipe structure 12, a plurality of grooves 70 to be fitted into and fixed to the back plate 68 are provided in advance in the longitudinal direction of the tubular body 66, the top plate 72 is removed, and the positions of the grooves 70 to which the back plate 68 is fixed are changed, whereby the length of the tubular body 66 can be adjusted. The tubular body 66 of the sound insulation system 10l shown in fig. 40 is a tubular body whose length of the tubular body 14 of the sound insulation system 10 shown in fig. 1 can be adjusted.

The tubular body 66 is preferably configured in a rectangular parallelepiped shape having an opening 76 by the back plate 68, the top plate 72, and the housing main body 74, and the back plate 68 and the top plate 72, the back plate 68 and the housing main body 74, and the top plate 72 and the housing main body 74 are preferably fixed in a detachable airtight manner by 1 set of magnets having different polarities, screws, or the like. Further, it is preferable that these adhesion fixing portions are hermetically sealed in advance.

By adjusting the position of the back plate 68 in this manner, tubular bodies (air column resonators) 66 having different lengths can be formed, and the sound insulation characteristics (phase difference of sound entering the tubular bodies 66 from the openings 76) can be adjusted.

The pipe structure 12 of the present invention has a curved structure including a straight pipe portion 16 and a curved portion 18 curved from the straight pipe portion 16. Here, the wind, (the flow of air) and the sound waves entering from the open end 22 of the curved portion 18 of the tube structure 12 collide with the wall surface of the corner portion of the tube structure 12 (the ceiling surface of the straight tube portion 16 facing the open end 22) and are reflected toward the upstream side (the open end 22 side). Therefore, both wind and sound waves are unlikely to flow from the open end 22 side to the open end 20 side of the straight tube portion 16 in the tube structure 12, and are unlikely to pass through the tube structure 12.

Therefore, in order to ensure air permeability, it is conceivable to reduce the angle change of the wall by forming the corner portion into a curved surface or the like, or to ensure air permeability by providing a flow regulating plate or the like at the corner portion to change the traveling direction of the wind.

However, when the corner portion is curved or the rectifying plate is provided at the corner portion, the air permeability is improved, but the transmittance of the sound wave is also increased.

Therefore, as in

sound insulation systems

10m and 10n shown in fig. 41 and 42, sound transmission walls 80 and 82 that transmit sound waves without allowing or preventing wind to pass through are disposed at the corner 17 of the pipe structure 12. As shown in fig. 41 and 42, the pipe structure 12 has a corner 17 bent at substantially 90 °.

In the sound insulation system 10m shown in fig. 41, the sound transmission wall 80 is disposed at the corner 17 of the tube structure 12 so as to be an inclined wall having a surface inclined at about 45 ° with respect to the longitudinal direction of the curved portion 18 of the tube structure 12 on the incident side and the longitudinal direction of the straight tube portion 16 of the tube structure 12 on the exit side.

In the sound insulation system 10n shown in fig. 42, the sound transmission wall 82 is disposed at the corner portion 17 of the pipe structure 12 so as to be a smooth curved surface (for example, an arc wall) protruding from the corner portion 17.

In fig. 41 and 42, the open end 22 side of the curved portion 18 is an incident side, and the open end 20 side of the straight tube portion 16 is an exit side.

In the

sound insulation systems

10m, 10n shown in fig. 41 and 42, the sound transmission walls 80 and 82 transmit sound waves, and therefore, sound waves incident from the upstream side transmit the sound transmission walls 80 and 82 at the corner portion 17 and are reflected toward the upstream side on the wall surface of the pipe structure 12. That is, the characteristics of the original pipe structure 12 without the sound transmission walls 80 and 82 are maintained. On the other hand, the sound transmission walls 80 and 82 do not pass wind, so the traveling direction of wind incident from the upstream side propagates to the downstream side at the corner 17 by the bending of the sound transmission walls 80 and 82. By disposing the sound transmission walls 80 and 82 in the corner portion 17 in this manner, the air permeability can be improved while maintaining the low sound transmittance.

As the sound transmission walls 80 and 82, a nonwoven fabric having a small density and a film having a small thickness and a small density can be used. Examples of the nonwoven fabric having a low density include TOMOEGAWA co, ltd: stainless steel fiber sheets (TomifleckSS), ordinary paper towels, and the like. Examples of the film having a small thickness and density include various commercially available wrap films, silicone rubber films, and metal foils.

In the present invention, as the sound insulation system 10o shown in fig. 43, a linear pipe structure 12c whose base end side is reduced in diameter can be used. The pipe structure 12c includes a straight pipe portion 16 having an open end 20 on one end side and a rectangular cross section, and a constricted pipe portion 84 having an open end 22 on the other end side and a rectangular cross section, and having one end side attached to the other end of the straight pipe portion 16. In the sound insulation system 10o of the present invention, the sound insulation structure such as the tubular body 14 is disposed at an appropriate position on the bottom surface inside the straight tube portion 16 of the tube structure 12 c.

In the present invention, as the pipe structure of the sound insulation system 10p shown in fig. 44, a T-shaped pipe structure 12d may be used. The pipe structure 12d includes a straight pipe portion 16 having an open end 20 on one end side and a rectangular cross section, and a pipe portion 86 having a rectangular cross section and having a side surface central portion attached to the other end portion of the straight pipe portion 16. One end of the tube portion 86 is an open end 22, and the other end is a closed end 38. The pipe portion 86 may be attached to the straight pipe portion 16 at a right angle or at an oblique angle. In the sound insulation system 10p of the present invention, the sound insulation structure such as the tubular body 14 is disposed at an appropriate position on the bottom surface inside the straight tube portion 16 of the tube structure 12 d.

In the present invention, as the pipe structure of the sound insulation system 10q shown in fig. 45, a crank type pipe structure 12e can be used. The pipe structure 12e includes a straight pipe portion 16 having an open end 20 on one end side and a rectangular cross section, a straight pipe portion 88 having an open end 22 on the other end side and a rectangular cross section, and a bent portion 18 having a rectangular cross section and connecting the other end of the straight pipe portion 16 and one end of the straight pipe portion 88. The angle of attachment of the bent portion 18 to the straight tube portions 16 and 88 may be a right angle or an oblique angle. In the sound insulation system 10q of the present invention, the sound insulation structure such as the tubular body 14 is disposed at an appropriate position on the bottom surface inside the straight tube portion 16 or 88 of the tube structure 12 e.

In the sound insulation systems 10o, 10p, and 10q according to the present invention, the sound insulation structure such as the tubular body 14 is disposed at an appropriate position on the bottom surface inside the straight tube portion 16 or 88 of the tube structures 12c, 12d, and 12e, respectively, whereby the peak value of the transmission loss due to the air column resonance and the peak value of the transmission loss due to the pipe coupling mode can be exhibited, as in the sound insulation system 10 shown in fig. 1.

Examples

The sound insulation system of the present invention will be specifically described with reference to examples.

First, using the tube structure 12 shown in fig. 2, the resonance of the tube structure 12 was measured, and the natural frequency fm of the tube structure 12 was measured.

As the pipe structure 12, a pipe structure in which the straight pipe portion 16 of the pipe structure 12 has a size of 88mm × 163mm (cross section) × 394mm (length) and the bent portion 18 has a size of 64mm × 163mm (cross section) × 27mm (length) was used.

When the natural frequency fm of the pipe structure 12 is measured, as shown in fig. 4A and 4B (hereinafter, represented by fig. 4A), a sound source (speaker) 26 and a sound pressure measuring microphone 28 are disposed in the pipe structure 12. The sound source 26 is disposed in close contact with the open end 22 of the bent portion 18 of the pipe structure 12. The microphone 28 is provided at a position spaced 500mm from the open end 20 of the straight tube portion 16 of the tube structure 12 and at a position spaced 500mm upward from the bottom surface 16a of the straight tube portion 16 of the tube structure 12.

When the sound source 26 and the microphone 28 are arranged at such positions, and the pipe structure 12 is provided and the pipe structure 12 is not provided as shown in fig. 4A, sound is generated from the sound source 26 and the sound pressure is measured by the microphone 28. From these measurements, the transmission loss of the tube structure 12 is calculated. The results are shown in FIG. 5.

From the results shown in fig. 5, fm1, fm2, and fm3, … … were determined from the low frequency side as the natural frequency (frequency of the natural mode of the tube structure 12) at which the transmission loss became minimum.

Next, the tubular body 14 shown in fig. 3 was used as the sound-insulating structure, and the resonance frequency fr of the sound-insulating structure was determined.

As the tubular body 14, a tubular body having a back surface length (back surface distance) d of 100mm, a height of 20mm and a width of 163mm, and a slit width of 20mm and a slit length of 163mm with respect to the slit size of the opening 24 was used.

In determining the resonance frequency fr of the tubular body 14 as the sound-insulating structure, the length of the back surface is d, the sound-insulating structure will pass through

fr [ Hz ] ═ v _ air/d/4(v _ air is speed of sound)

The obtained frequency is defined as a resonance frequency fr [ Hz ] of the tubular body 14.

Next, the phase differences θ 1 and θ 2 of embodiment 1 of the present invention are obtained.

The phase difference θ 1 was defined and obtained as follows.

The phase difference θ 1 represents a phase difference of the sound re-radiated from the sound insulating structure (the tubular body 14) with respect to the incident sound with respect to the sound incident to the sound insulating structure (the tubular body 14). For example, in the case of the tubular structure of the tubular body 14 used here, the approximate value of the phase difference θ 1 is obtained by the following equation from the length thereof.

θ1＝2d×(2π/λ)

The phase difference θ 2 is defined and obtained as follows.

In the case of the tubular body 14 which is a sound insulating structure, the phase difference θ 2 is obtained by the following equation, where L is the distance from the position Op of the opening 24 to the position of the pipe structure 12 where the sound pressure formed inside the pipe structure 12 becomes the maximum value.

θ2＝2L×(2π/λ)

The difference Δ θ between these phase differences θ 1 and θ 2 was obtained as | θ 1 — θ 2 |.

(lower frequency than resonance)

Here, let 343.5m/s be the sound velocity v _ air at 20 ℃, fr ≈ 850Hz because the back length d is 100 mm.

The maximum fm satisfying fm < fr is 600Hz, and fma is 600Hz (λ _fma＝572mm)。

The following equation was obtained for each La1 _fmaThe difference Δ θ of the sound (600Hz) was measured, and the transmission loss at this time was measured.

< measurement of the maximum value of the acoustic pressure inside the pipe structure 12 >

Inside the pipe structure 12, a position (for example, an antinode a) where the sound pressure at 600Hz is maximum was examined by shifting the position of the microphone tip from the open end 20 to a small point at a distance of 10mm from the bottom surface 16a of the pipe structure 12 by a measuring microphone 28 (type 4160n (1/4inch) manufactured by ACO corporation). As a result, it was found that the sound pressure was at the maximum at a position spaced apart by 100mm from the open end 20 of the pipe structure 12.

< measurement of Transmission loss >

First, a measurement system as shown in fig. 4A was prepared.

White noise is emitted from a sound source 26 (speaker (FE 103En manufactured by FOSTEX corporation)) provided on the side of the one open end 22 of the tube structure 12 in which the sound insulating structure, that is, the tubular body 14, is not provided, and a sound pressure p1 is measured with a measuring microphone 28 (type 4160n (1/4inch) manufactured by ACO corporation).

Next, a tubular body 14, which is a sound insulating structure, is provided inside the pipe structure 12. As a result, the measurement system shown in FIG. 6 was constructed. Here, the distance between the position Op of the opening 24 of the tubular body 14 and the position where the above-described sound pressure becomes the maximum (for example, the antinode a) is set to La1[ mm ].

La1 is defined below.

La1＝Lb-Lx(100mm)

Here, Lb is the distance between the position Op of the opening 24 of the tubular body 14 and the open end 20 of the tubular structure 12.

The sound pressure p2 was measured in the measurement system shown in fig. 6 by the same method as in the measurement system shown in fig. 4A.

The transmission loss is defined by the following equation.

Transmission loss (TL [ dB ] ═ 20log10(p1/p2)

(p 1: sound pressure when the tubular body 14 is not provided (refer to FIG. 4A), p 2: sound pressure when the tubular body 14 is provided (refer to FIG. 6))

The transmission loss was measured for various values of La1 (examples 1 to 4 and comparative examples 1 to 3).

The measured transmission loss of examples 1 to 4 and comparative examples 1 to 3 is shown in table 1 together with the distance Lb, the distance Lx, the distance La1, the phase difference θ 1, the phase difference θ 2, and the difference Δ θ ═ θ 1- θ 2 |.

The distance La1 is a distance from the position of the opening 24 of the tubular body 14 to the position of the tube structure 12 that is closest to the side in the same direction as the sound propagation direction at the frequency fma and that has the maximum value of the sound pressure. It cannot be defined when there is no maximum value on the side of the same direction as the propagation direction of sound. In table 1, the distance between the position closest to the maximum value of the sound and the position of the opening 24 of the tubular body 14 is shown as a positive value in the sound propagation direction, and therefore, some values become negative values.

[ Table 1]

As is clear from the results in table 1, in examples 1 to 4 satisfying the above formula (1), which is a requirement of the present invention, with respect to the sound of 600Hz, the transmission loss was relatively large as compared with comparative examples 1 to 3 which do not satisfy the above formula (1).

Fig. 27 shows the frequency dependence of the transmission loss in examples 1 to 4 and comparative examples 1 to 3. Fig. 29 shows the transmission loss and the relationship between the difference Δ θ between the phase difference θ 1 and the phase difference θ 2| θ 1 — θ 2| between examples 1 to 4 and comparative examples 1 to 3.

As is apparent from fig. 27 and 29, in examples 1 to 4 satisfying the above formula (1), which is a requirement of the present invention, the transmission loss is larger at a frequency around 600Hz than in comparative examples 1 to 3 which do not satisfy the above formula (1). It is also found that, as an additional effect, in examples 1 to 4, a high transmission loss of 3dB or more can be obtained at around 600Hz and 850Hz (fr), which is a resonance frequency.

As described above, in examples 1 to 4 satisfying the requirements of the present invention, high transmission loss can be exhibited in a plurality of frequencies.

At this time, the length d of the back surface of the tubular body 14 of the tubular structure is d < λ _fmaAnd/4, therefore, the acoustic insulation structure is smaller than the acoustic insulation structure based on air column resonance, but can realize higher transmission loss.

Next, the length d of the back surface of the tubular body 14 was measured by the same method as described above, assuming that it was 112 mm. From the measurement results, it was determined that the resonance frequency fr ≈ 750 Hz.

Then, the largest fm satisfying fm < fr was determined to be 600Hz, and fma-600 Hz was set.

The results in this case are shown in table 2.

[ Table 2]

From the results shown in table 2, it was found that, in examples 5 to 7 satisfying the above formula (1), which is a requirement of the present invention, the transmission loss was relatively large compared to comparative examples 4 to 5 which do not satisfy the above formula (1), with respect to the sound of 600 Hz. .

Further, fig. 28 shows the frequency dependence of the transmission loss in examples 5 to 7 and comparative examples 4 to 5.

As is apparent from fig. 28, in examples 5 to 7 satisfying the above formula (1), which is a requirement of the present invention, the transmission loss at a frequency around 600Hz is larger than in comparative examples 4 to 5 not satisfying the above formula (1). It is also found that, as an additional effect, in examples 5 to 7, a high transmission loss of 3dB or more can be obtained in the vicinity of both 600Hz and 750Hz (fr), which is the resonance frequency.

From the above results, it is shown that by satisfying the requirements of the present invention, the transmission loss with respect to sound of a frequency lower than the resonance frequency can be improved.

(higher frequency than resonance)

First, when the back length d is 100mm, fr ≈ 850Hz is determined.

On the other hand, when the back length d is 112mm, fr ≈ 750Hz is determined.

In any case, the minimum fm satisfying fm > fr is 1000Hz, and fmb is 1000 Hz.

In any case, the difference Δ θ with respect to the sound at 1000Hz was obtained for each La2, and the transmission loss at that time was measured.

Inside the pipe structure 12, a position (for example, an antinode a) where the sound pressure at 1000Hz is maximum was examined by shifting the position of the microphone tip from the open end 20 to a small point at a distance of 10mm from the bottom surface 16a of the pipe structure 12 by a measuring microphone 28 (type 4160n (1/4inch) manufactured by ACO corporation). As a result, it was found that the sound pressure was at the maximum at a position spaced apart from the open end 20 of the pipe structure 12 by a distance Lx of 50 mm.

< measurement of Transmission loss >

First, a measurement system as shown in fig. 4A was prepared.

Next, a tubular body 14, which is a sound insulating structure, is provided inside the pipe structure 12. As a result, the measurement system shown in FIG. 6 was constructed. Here, the distance between the position Op of the opening 24 of the tubular body 14 and the position where the above-described sound pressure becomes the maximum (for example, the antinode a) is set to La2[ mm ].

La2 is defined below.

La2＝Lb-Lx(50mm)

The transmission loss is defined by the following equation.

Transmission Loss (TL) [ dB ] ═ 20log10(p1/p2)

The transmission loss was measured for various values of La2 (examples 8 to 9 and comparative examples 6 to 7 when d was 100mm, and examples 10 to 11 and comparative examples 8 to 9 when d was 112 mm).

The measured transmission loss of examples 8 to 9 and comparative examples 6 to 7 is shown in table 3 together with the distance Lb, the distance Lx, the distance La1, the phase difference θ 1, the phase difference θ 2, and the difference Δ θ ═ θ 1- θ 2 |.

The measured transmission loss of examples 10 to 11 and comparative examples 8 to 9 is shown in table 4 together with the distance Lb, the distance Lx, the distance La1, the phase difference θ 1, the phase difference θ 2, and the difference Δ θ ═ θ 1- θ 2 |.

[ Table 3]

[ Table 4]

From the results in tables 3 and 4, it is found that, in examples 8 to 9 and examples 10 to 11 satisfying the requirement of the present invention, i.e., the above formula (1), the transmission loss is relatively large with respect to the sound of 1000Hz, compared with comparative examples 6 to 7 and comparative examples 8 to 9, respectively, which do not satisfy the above formula (1).

FIG. 30 shows the frequency dependence of the transmission loss in examples 8 to 9 and comparative examples 6 to 7. FIG. 31 shows the frequency dependence of the transmission loss in examples 10 to 11 and comparative examples 8 to 9.

As is apparent from fig. 30 and 31, in examples 8 to 9 and examples 10 to 11 satisfying the requirement of the present invention, i.e., the above formula (1), the transmission loss at a frequency around 1000Hz is larger than in comparative examples 6 to 7 and comparative examples 8 to 9, respectively, which do not satisfy the above formula (1). As is apparent from fig. 30, in examples 8 to 9, as an additional effect, a high transmission loss of 3dB or more was obtained in the vicinity of 850Hz (fr), which is a resonance frequency, together with 1000 Hz.

It is thus understood that in the cases of examples 8 to 9 and examples 10 to 11 which satisfy the requirements of the present invention, high transmission loss can be exhibited in a plurality of frequencies.

From the above results, it is shown that by satisfying the requirements of the present invention, the transmission loss can be improved for sounds of frequencies higher than resonance, which do not conform to the resonance frequency, in addition to the resonance frequency.

In conclusion, the effect of the present invention is obvious.

The sound insulation system of the present invention has been described in detail by way of various embodiments and examples, but the present invention is not limited to these embodiments and examples, and various improvements and modifications can be made without departing from the scope of the present invention.

Description of the symbols

10. 10a, 10b, 10c, 10d, 10e, 10f, 10g, 10h, 10i, 10j, 10k, 10l, 10m, 10 n-sound insulation system, 12a, 12 b-tube structure, 14a, 14b, 30, 66-tubular body, 16-straight tube portion, 16 a-bottom surface, 17-corner portion, 18-curved portion, 20, 22-open end, 24a, 24b, 36, 54, 76-open portion, 26-sound source (speaker), 28-microphone, 32-tubular body, 34, 52, 64-helmholtz resonator, 38-closed end, 40, 50-sound absorbing material, 42-sound absorbing material replacement member, 44-replacement mechanism, 46-intermediate material, 48-adhesive material, 56-cover, 58-frame body, 60a, 60 b-magnet, 62-screw, 68-back panel, 70-slot, 72-top panel, 74-frame body, 80, 82-sound transmission wall.

Claims

1. A sound insulation system, having: a tube structure having 1 or more open ends; and a sound insulating structure, said sound insulating system being characterized in that,

the sound insulation structure has an opening or a radiation surface through which sound is incident or radiated,

the opening or the radiating surface of the sound insulating structure is disposed inside the pipe structure,

defining a phase difference of a reradiated sound reradiated from the sound-deadening structure with respect to the incident sound as theta 1 for the incident sound incident to the sound-deadening structure,

for 1 or more maximum values of the sound pressure of the sound forming the sound pressure distribution within the pipe structure,

when a distance between the opening or the radiation surface of the sound insulation structure and a position of the pipe structure where the sound pressure is the maximum value is L, a wavelength of incident sound to the sound insulation structure is λ, and a phase difference θ 2 is defined as 2 π × 2L/λ,

satisfies the following formula (1):

|θ1-θ2|≤π/2……(1)。

2. the sound insulation system of claim 1,

the sound forming the sound pressure distribution in the pipe structure is a sound of the same frequency or wavelength as the incident sound incident to the sound insulation structure.

3. The sound insulation system according to claim 1 or 2,

the sound insulation structure is a resonance body for sound waves.

4. The sound insulation system according to any one of claims 1 to 3,

the maximum is an antinode of a standing wave of sound formed by the tube structure.

5. The sound insulation system according to any one of claims 1 to 4,

the tube structure has a resonance satisfying the above formula (1) at a frequency at which the resonance occurs.

6. The sound insulation system according to any one of claims 1 to 5,

the sound insulating structure is a tubular body having the opening.

7. The sound insulation system of claim 6,

the formula (1) is satisfied at a frequency different from the resonance frequency of the tubular body.

8. The sound insulation system of claim 7,

the transmission loss becomes maximum at the frequency satisfying the above equation (1).

9. The sound insulation system according to any one of claims 6 to 8,

the tubular body has a resonance frequency fr Hz,

at a maximum frequency fma [ Hz ] among frequencies at which transmission loss becomes minimum and less than the resonance frequency fr on the transmission loss spectrum of the tube structure,

the distance between the opening of the tubular body and the position of the tube structure closest to the opening on the same side as the propagation direction of sound and having the maximum sound pressure at the frequency fma is La1, and the wavelength at the frequency fma is λ _fmaWhen the compound satisfies the following formula (2):

0≤La1≤λ _fma/4……(2)。

10. a sound insulation system, having: a tube structure having 1 or more open ends; and a sound insulating structure, said sound insulating system being characterized in that,

the sound insulation structure is a tubular body having an opening,

the tubular body has a resonance frequency fr Hz,

a distance between the opening of the tubular body and a position of the tube structure closest to the opening on the same side as the propagation direction of sound and having a maximum value of sound pressure at the frequency fma is La1, and a wavelength at a frequency fma is λ _fmaWhen the compound satisfies the following formula (2):

0≤La1≤λ _fma/4……(2)。

11. the sound insulation system of claim 9 or 10,

when the back surface length of the tubular body is defined as d, the following formula (3) is satisfied:

d＜λ _fma/4……(3)。

12. the sound insulation system according to any one of claims 9 to 11,

the opening of the tubular body is arranged at a distance of the wavelength lambda from the open end of the tube structure _fmaAt an inward position.

13. The sound insulation system according to any one of claims 6 to 8,

the tubular body has a resonance frequency fr Hz,

at a frequency fmb [ Hz ] at which transmission loss becomes minimum in a transmission loss spectrum of the tube structure and is greater than a minimum of the frequencies of the resonance frequency fr,

the distance between the opening of the tubular body and the position of the tubular structure closest to the opening on the same side as the direction of sound propagation at the frequency fmb and having the maximum sound pressure is La2, and the wavelength at the frequency fmb is λ _fmbWhen the compound satisfies the following formula (4):

λ _fmb/4≤La2≤λ _fmb/2……(4)。

14. a sound insulation system, having: a tube structure having 1 or more open ends; and a sound insulating structure, said sound insulating system being characterized in that,

the sound insulation structure is a tubular body having an opening,

the tubular body has a resonance frequency fr Hz,

la2 is a distance between the opening of the tubular body and a position of the tube structure that is closest to the opening on the same side as a sound propagation direction and that has a maximum sound pressure at the frequency fmb, and λ is a wavelength at the frequency fmb _fmbWhen the compound satisfies the following formula (4):

λ _fmb/4≤La2≤λ _fmb/2……(4)。

15. the sound insulation system of claim 13 or 14,

the opening of the tubular body is arranged at a distance of the wavelength lambda from the open end of the tube structure _fmbAt an inward position.

16. The sound insulation system of any one of claims 6-15,

the opening portion of the tubular body is located at a position different from a node of a standing wave of sound formed by the tube structure.

17. The sound insulation system of any one of claims 1-16,

the opening or the radiating surface of the sound insulating structure is provided at a position within the wavelength λ from the open end of the tube structure.

18. The sound insulation system of any one of claims 1-17,

the sound insulating structure is built into the tube structure.

19. The sound insulation system of any one of claims 1-18,

the number of the sound insulation structures arranged inside the pipe structure is 2 or more.

20. The sound insulation system of any one of claims 1-19,

and a sound absorption material is also arranged inside the pipe structure.

21. The sound insulation system of claim 20,

the sound-absorbing material is provided to at least a part of the sound-insulating structure.

22. The sound insulation system of any one of claims 1-21,

the pipe structure and the sound insulation structure are integrally formed.

23. The sound insulation system of any one of claims 1-22,

the sound insulating structure is attachable to and detachable from the pipe structure.

24. The sound insulation system of any one of claims 1-23,

the sound insulation structure is a Helmholtz resonator.

25. The sound insulation system of any one of claims 1-24,

the sound insulation structure has at least a film and a back air layer sealed on the back of the film.

26. The sound insulation system of any one of claims 1-25,

when the sound insulation structure has a resonance frequency fr [ Hz ], fr is less than or equal to 1000 Hz.

27. The sound insulation system of any one of claims 1-26,

the tube structure is curved.